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In the past few weeks, it has been hard to miss the impact that Greta Thunberg, a Swedish schoolgirl, has had on the global politics of climate change. She has inspired millions of people to join the global climate strikes and addressed world leaders at the UN General Assembly. She has attracted a huge amount of praise and support, but she has also faced a noticeable amount of criticism. Her way of dealing with this has been to say that her message is simple. She has called for people to unite behind the science which shows the danger that we are all in from the rates at which climate is already changing. She points to the fact that it will be her and her peers who are going to be directly affected by the impact of climate change. What we all do now, or fail to do, to control the climate emergency we're in will have a huge impact on younger generations.

Extinction Rebellion (XR), a civil disobedience group campaigning to prompt action on the climate emergency, and co-founded by Roger Hallam,
Gail Bradbrook and others in the UK, have also had a major impact on the global politics of climate change. The response to XR has been similar— huge praise and support—but also a noticeable amount of criticism. XR’s way of dealing with this has been to say that their message is to speak the truth and encourage others to understand the dangers that we are all in from the rate at which the climate is already changing. They also say, let us all act together to prevent as much of this as is still possible.

Together these movements are strong and support for their message is growing rapidly. The good news is that they are achieving a level of public participation that many of us veterans have hoped for and worked towards for the past thirty years. What they are saying is exactly what the science is at last saying.

Some may ask, why at last? Hasn't the science always said this? The answer is no it hasn't.
It has been 'conservative', though from early days some have tried to counter-balance that.

Since the UK Climate Act in 2008, it had been asserted (wrongly) that an upper limit of 2.0° C was safe against the threats of runaway rates of climate change taking hold. It was not, nor is it. Notwithstanding that however, seven years of preparing IPCC AR 5 (published in 2015) were based on that assumption that it was safe, with the largely feedback-free Representative Concentration Pathway (RCP) policy-scenarios coming to dominate the output in its Summary for Policy Makers.

What is new and quite unique about this science is that for the first time in thirty years it focuses on [a] the projection of 1.5° C above pre-industrial as a lower and safer upper temperature limit [b] detailed climate and climate-feedback modelling and [c] remainder-global-carbon-budgeting to support this new temperature limit of 1.5° C.

This IPCC Special Report on 1.5° C on this matter (published in August 2018) engages with this. It is the result of the Paris Agreement of 2015 in which the demand to include the lower limit of 1.5° C was accepted because of enormous political pressure brought in the negotiations by the nations of the Climate Vulnerable Forum.

Most feedback-effects had been omitted from the climate-modelling used to prepare the RCPs. The shift in perceptions recently towards urgency is because of mounting evidence of accelerating rates of change, but it was also assisted by the admission by DECC in 2016 that these omissions had indeed been the case. This has been and remains a substantive issue, as does the issue of the base year for temperature rise.

The bad news is that the increasingly rapid rates of ocean warming, cryo-melt, sea-level rise, climate emergency related forest fires and rates of climate change are now starting to accelerate out of control.

We need to respond to the climate emergency at a quicker rate than it is being created. So, to solve the accelerating problem of atmosphere CO2 accumulation (at around 50% of emissions), solving it means acting faster than we're creating it. This means that we need to be removing our CO2 emissions to it at two times or three times or even four times the rate of emissions at which we are currently adding them (see here). That means very steep cuts in CO2 emissions need to start now. Unless this happens, the danger is that the still rising rates of emissions, concentrations, temperature and of changing climate will accelerate completely beyond our ability to control.

The IPCC Fifth Assessment report was published in 2015 and advocated a ceiling of around 2.0° C on global average temperature rise (RCP 2.5). However, the ‘Paris Agreement’ was agreed at the same time and central to this Agreement is the call to limit that rise to 1.5° C above pre-industrial levels. 1.5 ° C to stay alive cry the small island states already being immersed by sea-level rise & this is what we should all aim for.

A special report was commissioned from the IPCC to establish what would be necessary to limit global temperature rise to 1.5° C. It was published in August 2018 [see here & here]. It is behind this science that Greta Thunberg and XR are now calling for us all to unite.

Preventing the global temperature rise from going above 1.5° C above pre-industrial levels
with a 66% chance of success, requires us to achieve zero emissions globally by 2034
.

As things stand our emissions levels are above those projected in RCP 8.5. Nature magazine pointed out that the RCP 8.5 emissions path reaches Permian Extinction levels of atmospheric CO2 concentration & temperature, where it is estimated that 95% of all life forms were made extinct (see here & here).

In 1997, this piece in Nature helped to get agreement around contraction and convergence - the C&C Principle - at COP-3 in Kyoto Japan. Based on this principle, the UK Climate Change Act of 2008 set a target to reduce greenhouse gas emissions by 80% by 2050. Adair Turner, the chair of the committee said that if for reasons of urgency the rate at which reducing greenhouse gas emissions had to be increased, then for reasons of equity the rate of convergence had to be accelerated relative to that (see here & here).

This is obviously now the case. The school-strikers, XR and the science are showing us the way. Let us understand and support these remarkable efforts now. The UN Secretary General recently warned again forcefully that the race against the climate crisis is a race we are all losing & that to win demands urgent action.

Aubrey Meyer is one of the co-founders of the Global Commons Institute (GCI).
He has campaigned for thirty years on a campaign for UNFCCC-Compliance.

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