Why has President Biden committed the United States to cutting emissions by half by the end of the decade?

On Earth Day 2021 the United States hosted 40 world leaders at a virtual Leaders Summit on Climate at which President Biden said “the United States sets out on the road to cut greenhouse gases in half — in half by the end of this decade. … We know just how critically important that is because scientists tell us that this is the decisive decade.  This is the decade we must make decisions that will avoid the worst consequences of a climate crisis.”

Why half? Why this decade? Who are these scientists?

Cutting emissions in half is only half the story. The scientists are the IPCC, which stands for the Intergovernmental Panel on Climate Change and in 2018 they released a report in response to the 2015 Paris Agreement.

The Paris Agreement established the ambition of the governments of the world to keep warming well below 2°C, and preferably to 1.5°C.

The IPCC responded with that 2018 report describing the effects of 1.5°C of warming, plus the difference that half a degree Celsius – 2°C versus 1.5°C – would make. It turned out that only that extra half degree Celsius will make quite a considerable difference in the livability of planet earth. The worse news is that the trajectory of warming based on historical trends will see increases certainly above 3°C and possibly much more if emissions aren’t cut.

Calculations of something called a “carbon budget” indicate that to keep the world’s temperature at levels below “dangerous interference with the climate system” – as the language of international treaties describe it – the whole world must become carbon neutral by 2050.

Although the IPCC was formed in 1988 and the United Nations Framework Convention on Climate Change (UNFCCC) was agreed to in 1992, world emissions of greenhouse gases have gone up and up and up year after year after year almost without any pause – even in these COVID years.

A button imploring visitors to share the book "Because IPCC" on social media. The button has a background image of a boy reading a graphic novel (actually a Superman comic book).

So that means that by 2050, less than 30 years away, the world will have to have achieved an effective 100% reduction in emissions of greenhouse gasses. The logic of reducing emissions by 50% this decade is that the second half of the 100% will be harder to achieve and might take twice as long. The authority of the scientists of the IPCC is enough to convince not only President Biden but the governments of more countries than are members of the United Nations. Virtually every government in the world has ratified the UNFCCC and virtually every government in the world is a signatory to the Paris Agreement. The reason is that practically every government in the world participates in development of IPCC reports. The IPCC is made up of both scientists from all over the world who write the reports on what the science says, and official government representatives from countries all over the world who oversee and ultimately achieve consensus on what the reports contain.

The IPCC methods are as solid as humanly achievable. You can be confident of that because for every IPCC report all the scientists in the world convince all the nations in the world to come to a consensus.

For more info on the IPCC — in a digestible form — check out the book Because IPCC.

It’s a short, 33 illustrated pages, an upbeat, entertaining story that explains the history and science of the IPCC. The scene is 100 years in the future when the world has “solved” climate change and people are looking back, inspired by the dedication, rigor and achievements of the scientists of today.

Photo credits