Global warming is a scientific fact as much as the hole in the ozone layer or Earth’s orbit around the sun. Global temperature records have been broken three years running. Arctic Sea ice is declining rapidly. Sea levels are rising. For some societies, such as small island nations in the Pacific and Indian Oceans, environmental havoc is not a distant threat. It has arrived.
To reduce the risk of a global environmental catastrophe, and to avoid reversing the course of human progress, the world must urgently bend the curve of global emissions away from fossil fuels. Global warming must be kept below an increase of 2 degrees Celsius (3.6 degrees Fahrenheit); beyond that we will face major social and economic consequences.
The math to keep the increase below that critical level doesn’t get much simpler. Emissions must peak no later than 2020, and we must reach a fossil-fuel-free world economy by 2050.
National pledges made for the Paris Climate Agreement fall short. Indeed, the political landscape is dominated by governments willing to make only incremental progress: two steps forward and one step back, or giant leaps back, in the case of the United States, where President Trump has threatened to retreat from international climate action and has proposed devastating cuts in funding for climate science and international collaboration.
The vast divide between what is necessary and what politicians are willing to do leaves many scientists nervous that we could blow our last chance to reduce the grave risk to our environment and world stability.
Still, there are good reasons for cautious optimism. Despite the halting progress made by politicians, history shows that the modern world has been shaped by major moments of disruption. Think about the recent United States election, Brexit, the global financial crisis of 2008 and the rapid advances made in the technology sector in recent decades.
To help rethink the climate challenge, my colleagues and I developed an environmental corollary to Moore’s Law, which says that computing power doubles every 24 months. A “carbon law” states simply that the world must halve emissions every decade to stand a chance of reaching a stable climate system for the planet.
We emit about 40 gigatons of carbon dioxide a year. Assuming emissions start falling by 2020, and using the carbon law as our guide, we should halve carbon dioxide emissions to 20 gigatons by 2030. We then should reach 10 gigatons by 2040, and leave a small residual of five gigatons by 2050.
To make this happen, we must ramp up technology to pull carbon dioxide from the atmosphere, protect the oceans and land that absorb half of our emissions already, and transform the world’s food system from a major carbon emitter into a major carbon store.
A carbon law of halving emissions every decade can be adopted at all levels: for individuals, families, communities, companies, cities and nations. Those with the biggest carbon footprint need to do the most.
The global economy is on the right trajectory.
Global emissions growth from fossil fuels has plateaued for three years running, even with strong economic growth, thanks to efforts in China, but also progress in the United States, and some 20 other countries where net domestic emissions are declining. The renewable energy sector is expanding rapidly and employs more people in the United States than fossil fuels combined.
Installation of renewables in the energy sector is doubling every five to six years and has been on this course for a decade. If we keep doubling at this pace, renewables will reach 100 percent before 2050.
We can say good riddance to coal by around 2030, saving millions of lives as air quality improves. And bye-bye to oil by 2040. At this pace and scale, we can be close to carbon-free by 2050.
Johan Rockstrom is the director of Stockholm Resilience Center and professor of global sustainability at Stockholm University.