We are already experiencing climate change impacts, and this will be worse at 1.5 deg C above pre-industrial levels, and worse again at 2 deg C.
Based on current warming trends, sea ice, glaciers and coral reefs are on the way out. More intense extremes of heat, rainfall and storms are on the way in.
The imperative to act to prevent the worst of these impacts is strong. So, let's do it. Let's transform our societies to keep global warming below 1.5 deg C.
But can we do it?
Can the world limit global warming to below 1.5 deg C?
We are currently on a path to 3 deg C by 2100, based on current pledges to reduce emissions, so we're far off course.
The special report by the UN Intergovernmental Panel on Climate Change (IPCC) released last week did not pass judgment on whether 1.5 deg C is feasible. The report states only what is required. It says the 1.5 deg C pathway requires global emissions to be halved by 2030, reach net zero around 2050, and go negative thereafter.
What would it take to prevent 1.5 deg C of warming? It requires minimising energy consumption, growing non-fossil sources of energy (solar, wind, hydro, nuclear), closing fossil sources of energy (coal, oil, gas), minimising emissions from industry and agriculture, increasing forest cover, developing technologies to remove carbon from the atmosphere on a larger scale, and even putting aerosol particles in the upper atmosphere to reflect sunlight back into space.
Let that sink in.
We currently put 40 billion tonnes of carbon dioxide (CO2) in the atmosphere every year, and this is still increasing. But at the end of the century, we need to be removing five to 10 billion tonnes or more of CO2 from the atmosphere every year. That's because we have already put too much in.
We are in this predicament because we have left it until it is too late. This fact alone should make people reflect on whether 1.5 deg C is feasible in a world that has already warmed 1 deg C.
What would it take to prevent 1.5 deg C of warming?
It requires minimising energy consumption, growing non-fossil sources of energy (solar, wind, hydro, nuclear), closing fossil sources of energy (coal, oil, gas), minimising emissions from industry and agriculture, increasing forest cover, developing technologies to remove carbon from the atmosphere on a larger scale, and even putting aerosol particles in the upper atmosphere to reflect sunlight back into space.
This needs to happen in the context of sustainable development and efforts to eradicate poverty.
There is no easy way to 1.5 deg C. The list of requirements is long, and it is a list that every politician needs to take back to their countries and garner support for.
Human ingenuity can perhaps do anything, but there must be a desire to do it. Whether it is technically possible to keep below 1.5 deg C is not the right question. It is whether we as individuals in countries facing different challenges want to do it. Let's assume it is technically possible.
The real challenge for 1.5 deg C is to get politicians, supported by their constituencies, to put the frameworks and incentives in place to allow that transition to happen.
Societies, politics and the technical aspects need to align.
Societies also need to disrupt the incumbents and foster newcomers, while continuing to meet everyday needs such as food, shelter, health, education, and perhaps even a few luxuries.
The closer we want to get to 1.5 deg C, the more effort is required. The further we are away from 1.5 deg C, the riskier the climate impacts.
What is the lesser of those two evils? That is something I can't answer, nor the IPCC, but it is something that society will eventually find the answer to.
•The author is research director of the Centre for International Climate Research in Oslo. It was established by the government of Norway in 1990.