Here's what it would take to stop climate change sooner

One of the biggest surprises that led to the 2015 Paris International Agreement on Climate Change Emissions was the discussion on a new goal. The nations have set themselves the goal of limiting global warming to less than 2 ° C some time ago. Since then, most discussions have focused on the fact that our actions have not been sufficient to achieve this goal. But in Paris, some vulnerable nations decided to get up and say that 2.0 ° C was not good enough. Low-lying island countries, for example, have not only been negotiating to achieve an objective that might not even save them.

In the end, the Paris Agreement noted that countries were striving to keep warming "well below" 2 ° C. The problem, even with a slight shift in objectives, is that the scientific work carried out before the international negotiations have not yielded results for a scenario at 1.5 ° C.

While government officials are frankly buried under high quality scientific information that they really need to make informed decisions about the urgency of climate change mitigation, they have ordered a 1.5 ° addendum C. After overtime work in recent years, scientists who have volunteered for the Intergovernmental Panel on Climate Change (IPCC) have now provided a report summarizing the findings of existing research on climate change. a world of warmer 1.5 ° C.

Base gasoline is not surprising: the warming effects of 1.5 ° C are slightly below 2.0 ° C and it is harder to reduce greenhouse gas emissions fast enough to reach lower goal. However, when calculating numbers, some effects are particularly noticeable and the roadmap for reducing emissions becomes perfectly clear.

A new world

The report notes that we are currently warming to about 1.0 ° C, with an upward trend of 0.2 ± 0.1 ° C per decade. If we eliminate all of our emissions today, we would still see additional warming (for example, aerosol pollution reflecting sunlight quickly disappearing from the atmosphere), but probably not enough to allow us to pass imperiously. the limit of 1.5 ° C. Nevertheless, at our current rate, we should reach 1.5 ° C between 2030 and 2052.

Some impacts of climate change show particularly large jumps between 1.5 and 2.0 ° C. Heat waves, heavy rainfall and regional droughts are increasing considerably, as are their impacts on human health. Ecosystems, too, would benefit greatly from limiting global warming. Of the more than 100,000 terrestrial species studied, for example, their numbers are expected to disappear by half of their range. double between 1.5 and 2.0 ° C. Coral reefs have particularly dark prospects. We expect to lose 75-90% of coral reefs by 1.5 ° C; at 2.0 ° C this number is more than 99 percent.

The report estimates that the rise in sea level in 2100 would be about 10 centimeters less in a world of 1.5 ° C compared to a world of 2.0 ° C. This may seem little compared to worst-case scenarios of more than one meter of sea-level rise, which have often been discussed, but 10 million people live in areas that would be affected by this extra 10 centimeters.

Can we do it?

So, is it possible to steer the ship up to a limit of 1.5 ° C? It should be noted that we have not even promised enough action to bend at less than 3.0 ° C, let alone reach a lower goal, but it is not physics that prevents us from doing so. The report points to a number of technically possible ways to reduce emissions fast enough to stabilize the Earth's climate at 1.5 ° C, but margins are very meager.

The "good" news is that this ratio has slightly increased the estimated amount of greenhouse gases we can emit before crossing the limits of 1.5 ° C or 2.0 ° C (according to recent research that we presented). The bad news is that it would still require a herculean effort. To halt global warming to 1.5 ° C, global emissions are expected to decline by about 45 percent by 2030, barely more than a decade. By 2050, we will have to achieve net net emissions – all remaining emissions should be neutralized by the active phase-out of CO₂ of the atmosphere.

Compared to the already arduous task of achieving the 2.0 ° C target, this effort would require even more efficiencies to reduce total energy demand. Capturing emissions from natural gas plants and storing them underground would be necessary to allow faster cuts. Coal should be a remnant of the past. Transportation (and other sectors) should be electrified and operated on the new cleaner grid, rather than on fossil fuels. And the techniques of removing carbon dioxide from the atmosphere should be used on a truly significant scale.

If the world finds the political and personal will to mobilize and deploy such efforts, the report shows that these actions would benefit more than the climate alone. With regard to a set of UN-defined sustainable development goals, there are trade-offs, but most measures to limit global warming and its impacts would improve life in many ways. This would certainly require massive investments, but they would be profitable.

In short, the report's response to governments is that limiting warming to 1.5 ° C would bring great benefits, and it is still technically possible. We now know if governments will do anything with this knowledge.

At a press conference hosted by the IPCC Monday morning in Korea, Jim Skea of ​​Imperial College London asked a question about the importance of reforestation versus fossil fuel reductions as an opportunity to summarize the basic message of the report: "[S]The option x or the option there is not the way this report is framed. The word "or" does not work in relation to the 1.5 ° C warming ambition. The only binding word you can use is "and".[…] So, the bottom line is that the option x AND the option y AND the option z are the only We must really achieve this kind of ambition. "