This is in response to a “Nature comment” Climate tipping points — too risky to bet against which is scaring people. There are no new research findings in it and nothing to overturn the IPCC's conclusions. Of course it is important to look carefully at tipping points and the IPCC has done so with its high level reviews, and examined many research papers on the topic. The IPCC and climate scientists fully appreciate the importance and significance of tipping points. The reports are saying that factually the science doesn't support them in this case for global warming at the levels of CO2 emissions considered. Ecosystem tipping points are supported, though at 2°C this is only for corals .

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The claim of the authors is that we have a possibility of climate tipping points baked in that prevent us reaching the 1.5°C or even the 2°C goals. However, they provide no new evidence, or research findings to support this claim. A "Nature comment" is a little different from a normal Nature paper - it's a sort of scientific political comment. It argues and persuades rather as debaters do in politics. The BBC article has one mildly critical comment on it, but doesn’t go into detail. They mention that Professor Mike Hulme from Cambridge University put it like this:

“Their position is speculative; there are no new research findings presented here.

“Their mathematical ‘formula’ contradicts everything that social science and humanities scholarship tells us about public emergencies - namely that they result from political argument, reflection and judgement.

“Emergencies are declared by legitimate political actors; they are not calculated mathematically by self-appointed scientists.”

Is the climate passing some key 'tipping points'?

The scared people I help need a more detailed response than this. You can see my annotated version of it here, using, the academic web annotating tool:

This is another article I'm writing to support people we help in the Facebook Doomsday Debunked group, that find us because they get scared, sometimes to the point of feeling suicidal about it, by such stories.

Do share this with your friends if you find it useful, as they may be panicking too


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Here I am talking about this article in a video:

(click to watch on YouTube)

The IPCC report in 2018 said, in the summary for policy makers, that anthropogenic emissions so far have contributed 0.8 to 1.2° C since pre-industrial and that we have less than 0.5 C "baked in, and probably only 0.15 degrees and we can offset that with sharp reductions of methane and soot. That is why they concluded that it is scientifically possible to target 1.5 C.

Though there is an ecosystem tipping point at 2°C for the corals, the only climate tipping points identified on those paths are for ice melting that unfold over many thousands of years. The IPCC in 2018 concluded that though this can raise sea levels, it is not a global warming tipping point and can't prevent us remaining within 1.5°C even long term.

The permafrost thaw is also not able to do this. Although a significant amount will thaw this century and is already thawing, most of the thaw unfolds over centuries even on worst case scenarios, and is not enough of an effect to use up our remaining budget. The IPCC report on the Ocean and Cryosphere concluded that it can be largely offset by reducing human emissions of methane even in the worst case scenario. Also it is not yet clear if the thawing permafrost will be a carbon source or a carbon sink. It all depends on what happens to the organics from dead plants and animals trapped in the permafrost as they warm up and decompose. Even on high emissions scenarios there are some studies reviewed by the IPCC right up to 2018 that find that the permafrost can be a net sink through to 2100. These don't get as much publicity as the ones that say it will be a net source. See section of the 2019 Special Report on the Ocean and Cryosphere in a Changing Climate

The corals tipping point is serious enough and plenty of motivation to avoid a global warming of 2vC by itself, and there are many other reasons to increase our pledges to the 1.5°C path. However in the high level reviews of the literature by the IPCC to date, nothing in the science so far has identified anything that prevents us staying well below 2°C this century.

The authors of this Nature comment came to their conclusions by looking at only one side, for instance deforestation but not reafforestation, and by looking at processes that unfold gradually thousands of years into the future (on such long timescales we can surely do carbon sequestration from the atmosphere if our descendants decide it is needed). The clouds tipping point they mention requires more CO2 emissions than are possible this century (if you read the paper carefully it's 1300 ppm but they ignored some interactions that would likely increase that to somewhere between 1400 and 2200 ppm.).

The Amazon dieback according to recent research is a more gradual continuous process depending on the temperature and a large part of the Amazon is more resilient and survives under even high emissions scenarios.

They also have an uncited claim that zero emissions are not possible in less than 30 years. However there seems nothing to prevent a world goal of zero emissions by 2050 or less already. UK and California are already targeting zero emissions by 2050 and the EU just declared a climate emergency and the parliament has made a resolution to target zero emissions by 2050, the first stage of a process that may lead to a formal pledge by 2020. The UK opposition parties in the current general election are all more ambitious than that, targeting a range of dates from 2030 through to 2045, and Finland already target 2035, to give a few examples. Bernie Sanders Green New Deal targets 2030 for the US.

If we do target zero emissions by 2050 globally soon, it gives room to target zero emissions earlier than that with increased pledges. Such targets get easier as we gain experience and as the costs of renewables continue to plummet with new technology, for instance solar photovoltaic prices have decreased four fold in eight years and are expected to halve in price at least once more. There can also be new ideas such as Potential for carbon capture from giant kelp farming and the new Mexican idea of cultivating fermented Agave mixed with trees for feeding animals in dry areas which has potentially vast CO2 capture potential.

We are not doing enough yet but it is amazing how much we have done in the last five years. Psychologists tell us that positive messages work best. To encourage people to do more, we don't need to heighten the sense of urgency any more, and especially, not go beyond what the science says, clearly and plainly. We need to encourage more action with positive messages that what we are doing has already had an effect and about the potential for what we can do in the future.

See the section at the end of this article: At last we begin to act decisively


skip to At last we begin to act decisively

You can see my annotated version of it here, using, the academic web annotating tool:

Here they are with screen shots and links to each one:

We think that several cryosphere tipping points are dangerously close, but mitigating greenhouse-gas emissions could still slow down the inevitable accumulation of impacts and help us to adapt.

These unfold over centuries and millennia. Over the very long timescales of thousands of years we can take carbon dioxide out of the atmosphere to more than compensate for the CO2 we've added. We already have ways that could do this e.g. using giant sea kelp farming a low tech way that according to a preliminary paper could get us back down to pre-industrial by the end of this century for an Apollo moonshot level of funding.

Whether or not we can do such projects in a sustainable way this century, there is the possibility of such projects at some time over the next several centuries or millennia.

Potential for carbon capture from giant kelp farming

Modelling work suggests that it could add another 3–4 m to sea level on timescales beyond a century.

To put all this in perspective the latest Ocean and the Cryosphere report has narrowed the range of projections for the sea level rise from all sources, at the “likely” level of 17–83 percentile, to 0.29 - 0.59 meters at 1.5°C, 0.39 to 0.72 at 2.4°C and 0.61 to 1.10 m at 4.9°C.

Here RCP 2.6 is the 1.5°C path, RCP 4.5 is 2.4°C and RCP 8.5, Business as usual is the 4.9°C path.

This shows the regional sea level rise in meters

Figure 4.10:

This is a zoom in on the RCP 2.6 (1.5°C approx) in that figure

And this is the RCP 4.5 (roughly 2.4 C, not far from the 3 C path we are on now with existing Paris pledges)

This shows the impact on coastal cities and other systems at the various sea level rises:

Figure 4.3: Additional risk related to sea level rise for low-lying coastal areas by the end of the 21st century. The second column with the tick shows the result of adaptation. With adaptation then megacities are at moderate risk on all scenarios (Miami would be a rare exception because of the limestone that makes it vulnerable at high sea level risees because the sea seeps through it).

Models suggest that the Greenland ice sheet could be doomed at 1.5 °C of warming3, which could happen as soon as 2030.

Yes, we may even have crossed a tipping point already (could be as low as 0.8°C) but it takes a really long time. Even with "business as usual" continuing our CO2 emissions without any reduction through to 2200, which is impossible with renewables, it takes until 3000 for all the ice in Greenland to melt. It is not certain even then. Between 72 and 100% lost according to a recent study.

Contribution of the Greenland Ice Sheet to sea level over the next millennium (study publlished: June 2019)

This will aid adaptation, including the eventual resettling of large, low-lying population centres.

It helps to slow sea level rise. However, those affected are not necessarily going to migrate. In most cases, they can stay in place and much of it can be mitigated with dikes. Holland has been doing that for centuries and some parts of Rotterdam are over 6 meters below sea level, so it is not high tech. Bangladesh, for instance, is reclaiming land at the same time that it is losing it with the help of advice from Dutch experts.

This for instance shows the potential reclamation areas for Bangladesh in a potential project similar to the Dutch polders in their Bangladesh Delta Plan:

Bangladesh Delta Plan (BDP) 2100

Only Florida is unable to do this because the limestone is porous and just lets water through. Details with links here:

Rising Seas - Ingenious Ways Netherlands, Florida And Bangladesh Can Adapt - Barriers And Sponges - And Floating Gardens

several of which involve sea ice.

The melting of the Arctic sea ice is not a tipping point either, according to the report (see Sea Ice).

"Sea ice is often cited as a tipping point in the climate system. Detailed modelling of sea ice, however, suggests that summer sea ice can return within a few years after its artificial removal for climates in the late 20th and early 21st centuries. Further studies modelled the removal of sea ice by raising CO2 concentrations and studied subsequent regrowth by lowering CO2. These studies suggest that changes in Arctic sea ice are neither irreversible nor exhibit bifurcation behaviour. It is therefore plausible that the extent of Arctic sea ice may quickly re-equilibrate to the end-of-century climate under an overshoot scenario. "

The main reason the Arctic is warming faster than the tropics is for the same reason northern Europe and northern America is - because of convection from the tropics which increases in a warming world. You get the same effect on a pure aqua planet

This shows the latitude dependent effect of a doubling of CO2 on an aquaplanet with no land or ice with a general circulation model

"Polar amplification of surface warming on an aquaplanet in "ghost forcing" experiments without sea ice feedbacks"

The main reason this doesn't happen in Antarctica is because of the strong westerly winds in the southern hemisphere that block the movement of heat from the tropics towards the south pole. Why Antarctica is not getting any warmer

As soon as we reach zero emissions the Arctic ice then it is in steady state and will slowly being to heal as some of the excess CO₂ leaves the atmosphere.

The ice albedo effect in the Arctic is minor and only local - it doesn't warm up the world as a whole when the ice melts.

Annotated version of image from Arctic albedo changes are small compared with changes in cloud cover in the tropics

Estimates of where an Amazon tipping point could lie range from 40% deforestation to just 20% forest-cover loss

The balance of latest research is more in the direction of a continuous change rather than a tipping point beyond which you can't restore the Amazon. The older research used simple models with only two plant functional types and not accounting for details like a range of tree ages and nutrients and other details. More recent models with more diversity of vegetation find it more resilient and likely to change in patches rather than all at once. The Amazon has also survived much drier conditions in the past, though not identical in all respects.

It also depends on the CO2 fertilization effect and how much this is increasing the biomass of the forests. Although a mass dieback is not looking likely it is 100 times less expensive to act to prevent it using no regrets measures that help anyway. See Limiting the high impacts of Amazon forest dieback with no-regrets science and policy action

The Royal Society review of research in 2017 said

Amazon rainforest: The processes acting on tropical rainforests are very complex and a recent review still emphasised the possibility of a climate threshold … Recent work using a detailed ecosystem model (Levine et al., 2016) supports the possibility of a significant but heterogeneous [not uniform] transition in biomass type dependent on the length of the dry season, but in a continuous rather than “tipping point” manner. Resilience may be underestimated if plant trait diversity is not included in models

See also this paper in Nature, 2016: Resilience of Amazon forests emerges from plant trait diversity

Parts of the Amazon seem much more resilient to warming and this is how it survived the last glacial minimum.

The upper picture here is the last glacial minimum and the lower picture is the end of the 21st century:

Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

North American boreal forests, potentially turning some regions from a carbon sink to a carbon source

Overall biomass is increasing in the Arctic region (as it is over most of the world)

Epstein et al (2012) found an average circumpolar increase in aboveground tundra biomass of 19.8% between 1982 and 2010.This increase was accentuated in the mid- to southern tundra subzones (20–26% increase), yet it was substantially less in the more northern tundra (2–7%).

Decline in greenness has recently been detected especially during the last 3–4 years

Changes in timing of spring snow melt, permafrost degradation, killing frosts due to mid-winter or early-spring snow melt, or vegetation shift from graminoids to deciduous shrubs are all possible reasons for arctic tundra browning.

For the boreal forest, remote sensing studies continue to support the “browning” of forest vegetation (1982–2008) with increasing drought stress as the most probable driver. However, this reduction in photosynthesizing vegetation appears to be related to the fractions of evergreen trees and deciduous trees on the landscape – with greater declines in evergreen-dominated areas (Miles and Esau, 2016). Changes towards greening or browning appear here as well highly variable, both in time and space.

The changing colors of the Arctic: from greening to browning

release carbon dioxide and methane

It doesn't really release it - there are organics from grass and animals and as it thaws and they decompose it can add to the soil carbon or be decomposed and released as methane (if it happens in damp conditions near the surface) or carbon dioxide. Meanwhile the thawing permafrost also supports grass, trees and peat which take up carbon dioxide. It's not clear if it will be a net sink or a net source of carbon with studies right up to the 2019 report that have it both ways even at high emissions. The date here is the date of the study and the bars show the change by 2100.

From section of the 2019 Special Report on the Ocean and Cryosphere in a Changing Climate

A recent paper in 2019 cited by the 2019 IPCC report finds that total emissions of methane from the permafrost can be more than offset by reductions in human anthropogenic emissions of methane. They cited it as:

As with total carbon emissions, there is high confidence that mitigation of anthropogenic methane sources could help to dampen the impact of increased methane emissions from the Arctic and boreal regions (Christensen et al., 2019).

The paper they cite is here:

Tracing the climate signal: mitigation of anthropogenic methane emissions can outweigh a large Arctic natural emission increase

Current legislation emission (CLE) and maximum technically feasible reduction (MFR) scenarios for anthropogenic methane reduction These are the four scenarios they look at in that paper:

  • No change - Arctic emissions unaffected
  • Modest: Tundra increases markedly, rest unaffected (50 Tg a year)
  • Large: Tundra and lakes increase markedly, ocean emissions double (100 Tg a year)
  • Extreme: Tundra and lakes increase markedly, extreme increase in ocean emissions (150 Tg a year)

Even the extreme scenario if combined with the maximum feasible reductions results in only a slight increase from the present. The scenarios are not correlated with particular emissions scenarios in that paper but the extreme scenario is unlikely for low emissions.

Amazon dieback could release another 90 Gt CO2

We need to bear in mind that there is global afforestation happening as well, also reversing desertification - this is just looking at forest loss without the gains. Asia, Northern Europe, Northern America, are all increasing in forest cover. China is one of the regions of most rapid increase. Only South America and Africa still have decreasing forest cover and that may turn around soon.

A recent study, 2019 attempts an integrated model for Brazil projecting to the future. Their model assumes that:

  • Crop yields [per hectare] will grow on average 1.5% per year while meat production will intensify linearly from an average base-year value of 1.0 to 1.7 heads per hectare by 2050.
  • Food intake grows with a 17.3% increase in food crops and 29.3% in meat products by 2050
  • The regions with the highest demand growth rates are the Centre-West, with a demand increase of 36.5% for food crops and 48.2% for meat, and the North with 34.6% and 45.8% for crops and meat respectively. One scenario explores the expansion of sugarcane on the cleared agricultural land (sugarcane expansion scenario), while the second scenario assumes an exclusive reforestation process (reforestation scenario). This shows how their model predicts a lot of freed agricultural land due to the increasing yields:

Agricultural land (crops, pasture, bioenergy and silviculture) peaks by 2020 reaching 292 Mha (an increase of 3.5%). It then liberates land at a rate of 6.0% annually, occupying 230 Mha by 2050, thus liberating 68 Mha of land or 8.0% of the total Brazilian territory. The Centre-West region, with typical large pasture lands, liberates 23 Mha, followed by the North (14 Mha) and South-East (13 Mha). Natural forest land is reduced from 459 Mha to 443 Mha by 2050., most of that in the first 15 years (2010–2025), with the Centre-West responsible of 85% (13 Mha) of the total deforestation With this scenario, then they compare growing sugarcane for biofuels on the cleared land with reafforestation. This is the result:

Their conclusion is that reafforestation of the regions that are freed up due to the reduced land area demands from agriculture will be able to recover the original carbon stocks of the felled forests by 2035 (this would be a larger area reafforested than was deforested in the first 15 years since 2010). But if you use sugarcane to make biofuels from the same area, even with carbon capture and storage, it is not able to totally offset the losses due to deforestation in the first 15 years. This is not taking account of practical issues and regulations, e.g. demand for the ethanol made from sugarcane and limitations on the amount of sugarcane plantations that are permitted. With their reafforestation they just look at the forest returning and not managed forests. They don’t seem to mention this, but if you had a manged forest and felled some of the trees for biofuel emissions carbon capture and storage you could be removing more CO2 than an old growth forest per hectare constantly through to the end of the century.

it highlights that the Earth system has been unstable across multiple timescales before, under relatively weak forcing caused by changes in Earth’s orbit.

It's not known for sure what caused them. Also they are a see-saw effect, sometimes a 10 C warming in the Arctic but simultaneously the southern hemisphere cools. Then the Arctic gradually cools and the southern hemisphere warms. Possibly quasi-irregular fluctuations that last for centuries instead of decades according to one paper in 2019 Coupled atmosphere-ice-ocean dynamics in Dansgaard-Oeschger events. Whatever the cause they only happen at times when Earth has large ice sheets. They seem to be a result of the ice albedo effect for such large areas of ice combined with the effect of the melting ice on the salinity of the northern Atlantic stopping the AMOC and also atmospheric heat transport as well. But whatever the details it depends on the large amounts of sea ice in the northern atlantic, well above what we have today and it is more of a redistribution of heat than a global warming.

a cloud-resolving model published this year suggests that the abrupt break-up of stratocumulus cloud above about 1,200 parts per million of CO2 could have resulted in roughly 8 °C of global warming

In their models the clouds weakening starts at 1,200 ppm, but the transition is at 1,300 ppm:

"Eventually, at sufficiently high greenhouse gas concentrations (1,300 ppm in our simulation without subsidence changes), stratocumulus decks break up into cumulus clouds, which leads to dramatic surface warming"

However they explain that they ignored some interactions that would likely increase that perhaps to somewhere between 1400 and 2200 ppm.

In particular, the large-scale subsidence in the troposphere weakens under warming32, which lifts the cloud tops and counteracts the instability15,19,24. Indeed, when we weaken the parameterized large-scale subsidence by 1 or 3% per Kelvin of tropical SST increase (within the range of GCM responses to warming33), the stratocumulus instability occurs at higher CO2 levels: around 1,400 ppm with 1% K–1 subsidence weakening, and around 2,200 ppm with 3% K–

So, their model suggests that this may happen somewhere between 1400 and 2200 ppm, more than triple current levels, which we won’t reach until the next century even at business as usual.

They continue

Equivalent CO2 concentrations around 1,300 ppm—the lowest level at which the stratocumulus instability occurred in our simulations—can be reached within a century under high-emission scenarios41. However, it remains uncertain at which CO2 level the stratocumulus instability occurs because we had to parameterize rather than resolve the large-scale dynamics that interact with cloud cover. To be able to quantify more precisely at which CO2 level the stratocumulus instability occurs, how it interacts with large-scale dynamics and what its global effects are, it is imperative to improve the parameterizations of clouds and turbulence in climate models.

It is important and may explain the past climates if it is true but is not a tipping point we can reach this century.

Paper can be read via the readcube free access link here on the author's website.

Many more results are pending and further investigation is required, but to us, these preliminary results hint that a global tipping point is possible.

The new model results don't fit with paleo and instrumental data

Shows the range of high, low and the black dot shows the best estimate for each method.

From: Explainer: How scientists estimate climate sensitivity (Carbon Brief)

Weather Underground published a comment on this by the climate researcher Peter Cox of the University of Exeter. a researcher into Equilibrium Climate Sensitivity:

“It is worth noting that observational constraints from both the temperature trend and temperature variability still suggest ECS of around 3°C. So climate science has a conundrum to solve here.”

New Models Point to More Global Warming Than We Expected

The next IPCC report may not lean on the models as heavily as previous ones:

In assessing how fast climate may change, the next IPCC report probably won’t lean as heavily on models as past reports did, says Thorsten Mauritsen, a climate scientist at Stockholm University and an IPCC author. It will look to other evidence as well, in particular a large study in preparation that will use ancient climates and observations of recent climate change to constrain sensitivity. IPCC is also not likely to give projections from all the models equal weight, Fyfe adds, instead weighing results by each model’s credibility.

New climate models predict a warming surge

More links here

To err on the side of danger is not a responsible option.

This is the precautionary principle and indeed is correct. One formulation of it is:

When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically.

Wingspread Conference on the Precautionary Principle

However, it doesn't say

When an activity raises threats of harm to human health or the environment, precautionary measures should be taken to prevent any claimed catastrophic event even if the scientific evidence is against it.

We need to act even if some cause and effect relationships are not fully established scientifically. However there has to be a scientifically credible basis for it, and so far this article hasn't established this.

If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization

This also doesn't follow. They are talking about a situation where we have already used up our CO2 budget for 2 C. This is similar to the effect of the Paris agreement falling apart. There is no possibility of that happening at present - but if that were to happen, and we do too little too late, and reach 3 C instead of 1.5 C, this would mean we get the harmful effects of a 3 C rise, but those are not an existential threat to our civilization. They could be an existential threat to several small island states and some local communities.

The IPCC's own example of a worst case scenario in the 2018 report is

“Scenario 3 [one possible storyline among worst-case scenarios]:Mitigation: uncoordinated action, major actions late in the 21st century, 3°C of warming in 2100

“In 2020, despite past pledges, the international support for the Paris Agreement starts to wane.”

“Several small island states give up hope of survival in their locations and look to an increasingly fragmented global community for refuge. Aggregate economic damages are substantial, owing to the combined effects of climate changes, political instability, and losses of ecosystem services.”

“The general health and well-being of people is substantially reduced compared to the conditions in 2020 and continues to worsen over the following decades.”

Cross-Chapter Box 8, Table 2, page 280 of chapter 3, Impacts of 1.5°C global warming on natural and human systems

IPBES finds that with high emissions scenarios we contiknue to feed everyone, but in a biodiversity reduced world with a reduced safety net and diminished food security. We risk falling back on our sustainable development goals to worse conditions than we have in 2020. Chapter 4. Plausible futures of nature, its contributions to people and their good quality of life

It is summarized by Almud Arneth in the press conference as

(click to watch on YouTube)

59:09 So could I perhaps ask Sandra Diaz if you could please respond to the AP question from Seth Borenstein about plain language by 2050. … For more precise numbers I would again invite our coordinating lead author Almud Arneth …

I think the question is what will the world look like in 2050. It is our choice it is purely our choice. None of the scenarios we've been exploring would indicate that we cannot feed the world or cannot provide water cannot provide shelter that's for sure. But we can do it in a sustainable way or we can do it in an unsustainable way and that is really our choice.

Here is Almud Arneth, the co-ordinating lead author for that section of the IPBES report again:

(click to watch on YouTube)

Hello, my name is Almut Arneth. I am professor at Kayati in Germany, and my role in this assessment was co-ordinating lead author in the chapter about future scenarios. So with scenarios what we are trying to do, we are exploring how the world could look like in 2050 or even in 2100. Fortunately the scenarios where we try to drive a more sustainable future, more equitable distribution of resources, is a much better outcome in terms of both still providing food, to feed and fibre to everyone on this planet, but at the same time decoupling that increasing provision of ecosystem services from the destruction of nature. We can do it if we choose to operate along those more sustainable distributions of resources.

I discuss it with examples of what we are doing here We can grow enough food for everyone through to 2100 and beyond on all scenarios

We argue that the intervention time left to prevent tipping could already have shrunk towards zero

This has not been established. There are no new research findings in this article to override the conclusions of the IPCC report in 2018.

This said, in the summary for policy makers, that anthropogenic emissions so far have contributed 0.8 to 1.2° C since pre-industrial and that the emissions so far have will have effects that last for centuries to millennia, such as sea level rise and associated impacts, but these are unlikely to cause even a long term global warming of 1.5°C (medium confidence) and that with high confidence this is not possible over the next few decades. This is the figure they use to illustrate it: Even the purple path with no reduction in non CO2 radiation forcing (such as methane emissions and soot) doesn't have any increases or tipping points.

A.2. Warming from anthropogenic emissions from the pre-industrial period to the present will persist for centuries to millennia and will continue to cause further long-term changes in the climate system, such as sea level rise, with associated impacts (high confidence), but these emissions alone are unlikely to cause global warming of 1.5°C (medium confidence). (Figure SPM.1) {1.2, 3.3, Figure 1.5}

A.2.1. Anthropogenic emissions (including greenhouse gases, aerosols and their precursors) up to the present are unlikely to cause further warming of more than 0.5°C over the next two to three decades (high confidence) or on a century time scale (medium confidence). {1.2.4, Figure 1.5}

There may be some temperature rise “baked in” as a result of the masking effect of SO2 aerosols from coal burning and the like, which cool the planet down slightly, but if so, it’s only a fraction of a degree, around 0.15 °C and if we stop the CO2, and remove the black soot (which has a warming effect) at the same time as we reduce the SO2, we can prevent even that.

Global Warming of 1.5 ºC - chapter 1, figure 1.5

If we stop all aerosol emissions, yellow line, there is a short term bump in temperature by 0.15 degrees, and returning to the previous temperatures in 20 years and ending with a reduction to 0.25 °C below the present by 2100

the reaction time to achieve net zero emissions is 30 years at best

Uncited assertion with no reasoning supplied for it. . Many countries already target zero emissions by 2050 or earlier, with the UK already targeting 2050 and all the opposition parties in the current election have earlier targets (2045 for SNP and LibDems, 2030 for the Green party, some time in the 2030s for Labour).

There seems nothing technologically infeasible about an earlier goal.

The average lifetime of a car at scrappage was 13.9 years in the US in 2015., and of an oil tanker, 20 years. Over timescales of 20 years or so, it can be done mainly through replacement of existing infrastructure and can be speeded up further through incentives and buy back programs.

With an earlier target, fossil fuel plants have to retire early, or be used at less than capacity. However those have low construction costs compared with renewables and high ongoing costs for the fuel. The fall in prices for renewables have already made them some of uncompetitive with renewables without subsidies. Some are retiring early already because of the competition from renewables.

By way of example, VCE finds that 74% of coal fired power stations in the US are at risk, with renewables costing less than fossil fuel power generation by 2025 and assuming technology continues to reduce in price for renewables, then half the coal fired power stations in the US are substantially at risk of closure by 2025 where by substantially at risk they mean that renewables will cost 25% less than coal.

By 2025, local wind and solar could respectively replace roughly 76 GW and 111 GW of coal generation at 25 percent lower costs than running the coal-fired power plants. Combining the wind and solar data sets, VCE finds that 211 GW of coal capacity, or 74 percent, is at risk with 94 GW substantially at risk from 2018 possible local wind and solar. Assuming the NREL lower cost technology baseline case for 2025, substantially at-risk coal increases to 140 GW (with sunset tax support), or almost half of the U.S. fleet.

The coal cost crossover:economicviability of existing coal compared to newlocal wind and solar resources

That is without any incentives, we may get half the coal fired power stations or more retiring by 2025, and could get nearly all of them retired as soon as that with some incentives to favour renewables.

With enough political will there is nothing scientific to prevent us increasing pledges in 2020 to achieve net zero by 2050. Though that is unlikely at present, without the US, we can pledge to substantially below 2.9 C. With future pledges in 2025 and 2030 we can increase our ambition to well below 2 C and below 1.5 C is not scientiically impossible.

The EU parliament has just now declared a climate emergency with three resolutions:

  • Commission must ensure all proposals are aligned with 1.5 °C target
  • EU should cut emissions by 55% by 2030 to become climate neutral by 2050
  • Calls to reduce global emissions from shipping and aviation

Finland already targets 2035 and unlike Norway which targets 2030, they don't plan to do it by buying carbon credits, but entirely through internal changes.

Finland to be carbon neutral by 2035. One of the fastest targets ever set

This is the basis of it

Finnish energy system can be made 100% fossil free

Bernie Sanders plan for the US targets 2030 for zero emissions. I discuss it here:

Does Bernie Sanders $16 Trillion Green New Deal Pay For Itself?


skip to Positive Motivation

I see it differently from most. I have been interested since before the subject began - as a young teenager keen on science in the 1960s, they knew so little they were talking about a possible near future ice age. We have known about global warming for decades. We have had politicians urging us to act since Margaret Thatcher made her speeches to the UN in 1989 (she was the first politician to do this, as one of the few politicians with a science degree - she was a professional X-ray crystallographer before she became a politician). Scientists had warned of this since the 1970s.

Here is Margaret Thatcher talking to the UN in 1989. It's interesting historically how much is the same between then and now.

(click to watch on YouTube)

Yet we did almost nothing for decades.

People start something in a big way in 2015. I am amazed by how much we have done. We now have renewables that have dropped in price four-fold in just eight years.

(from the UN report)

It’s reached the point where for most of the world, renewables already are the cheapest source of new power generation, and projected to compete with the operating cost of existing powerplants by 2020 (meaning it would be no longer economic to keep them running in the competition with renewables):

We have already knocked around two degrees off the predicted amount of warming for 2100. This is just the first five year phase of the Paris Agreement with increased pledges needed in 2020, 2025, 2030 and so on.

5 years later despair.


See also my


Skip to So much you can do yourself

We need to motiate ourselves with positive messages, not just focus on what is going wrong. Psychologically this is very important in terms of the narrative, to help us to move in the direction of doing something about all this. We already are but a more positive approach may help us do this more effectively.

This talk may help you if you are thinking about how to motivate both yourself and others, and also governments, to act on climate change:

(click to watch on YouTube)

To help motivate you you may like to watch some of these videos of some of all the positive things happening in the world as regards climate change.

Videos of good things that are happening in the world for climate change and biodiversity


Skip to Please Comment

Many feel helpless, faced by climate change and biodiversity loss. Other people and governments seem to be doing nothing (actually they are doing lots but the news is not shared). There seems nothing they can do personally and the whole thing seems hopeless.

This is so far from true. One person can’t do much but collectively through our life choices we can help transform the planet. Indeed, governments can’t do it by themselves, we are needed too.

The IPCC, and IPBES say a transformative change is needed at all levels in our society to combat climate change and biodiversity loss. This is empowering because it means there is much we can do ourselves already, even if we are in a country where the government is not yet doing anything.

They say that we need changes at a personal level complemented by changes at community levels, and government levels. We also need intergovernmental co-operation and co-operation of cities and communities that cross national boundaries as well as collaboration between governments and local communities.

To take a familiar example, recycling would never work if people didn't separate their rubbish and put it in the appropriate recycling bins. That transformation happened in the UK in my lifetime - in the 60s and 70s hardly anyone recycled. Now just about everyone does, in the UK at least.

It’s the same with food waste, once consumers realize that it is a significant issue for the environment and the planet, they are likely to voluntarily choose to act to reduce the amount of food they waste in the kitchen.

It’s the same also with meat. Once we know about the impact of intensively farmed meat on the planet, then many may choose to eat less meat. This is working already. We don’t all need to act, it’s enough if a significant number of us do, to make a big difference.

You do not have to do all of these things, or any of them. It may help to think it more in a positive way. If you want to help the planet, these are all things you can do that will make a difference, if significant numbers of us do the same.

There are many excellent and strong reasons to act promptly on climate change. It is important to combine food security with preserving biodiversity and nature services. But IPBES made it clear we don't face a future where it is impossible to grow enough crops to feed everyone.

12 Simple lifestyle changes to help reduce global warming and biodiversity loss

See also

Positive side of climate change facts, after two years of action, heading for 3°C with 1.5°C well within reach

Debunked - that we are in the middle of the sixth mass extinction

Let’s save a million species, and make biodiversity great again - UN report says we know how do it

Yes our generation’s children are headed for a world with nature and wonder in it - and their children too

Rising Seas - Ingenious Ways Netherlands, Florida And Bangladesh Can Adapt - Barriers And Sponges - And Floating Gardens

No Scientific Cliff Edge Of 12 Years To Save Planet (or 18 Months) - Can IPCC Challenge 'Deadlines Make Headlines' Misreporting?

24 Ways World Is Better - Famine Hugely Reduced - Literacy Soaring - Life Expectancy Up - Degraded Landscapes Restored, ... good news journalists rarely share

We can grow enough food for everyone through to 2100 and beyond on all scenarios

Some of the worst doomsday fear fact checking errors in the mainstream press - most are about climate change

How well are countries doing with their 2015 Paris pledges?


If you see any mistakes in this however small, or have any suggestions or questions, be sure to comment below, thanks!

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Seven tips for dealing with doomsday fears

If you are scared: Seven tips for dealing with doomsday fears which also talks about health professionals and how they can help.

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If you are suicidal don’t forget there’s always help a phone call away with the List of suicide crisis lines - Wikipedia