The bad news is that, despite these positive developments, enough damage has been done to the climate that time is running out.

The development of renewable resources is unstoppable. There are already more solar industry jobs than coal-mining jobs in the United States. The costs of wind and solar power are falling dramatically. Revoking the federal subsidies for solar and wind power would take congressional action, and, according to the American Wind Energy Association, 80 percent of all wind farms are in Republican congressional districts. The future of coal-generated electricity is grim, due far less to environmental regulation than to the relatively low cost of natural gas.

Despite the attack the Trump team is now mounting against responsible climate policy, there are still glimmers of hope.


No responsible person disputes that greenhouse gas emissions, chief among them carbon dioxide, are the major cause of climate change. Virtually all of the world’s climate scientists agree that to avoid the most dangerous effects of climate change we need to keep the increase in global average temperatures by the end of the century “well below” 2 degrees Celsius above pre-industrial levels.

Even if the Obama administration’s policies — like the Paris Agreement, the Clean Power Plan, and strict automobile and appliance standards — were fully implemented, we would be nowhere close to that target. According to the UN Environment Program, even if the carbon reduction pledges made in Paris are honored, the world is heading toward a likely temperature rise of 2.9 to 3.4 degrees this century.

The world’s foremost scientific expert body on climate change, the United Nations Intergovernmental Panel on Climate Change, or IPCC, has developed the concept of a “carbon budget.” That’s the amount of carbon dioxide that can be emitted into the atmosphere without causing the earth’s average temperature increase to exceed the target of 1.5 degrees (i.e., “well below” 2 degrees) or 2 degrees by the end of the century.


The carbon budget is like a credit card, where each month of charges increases the unpaid balance, making it harder and harder to pay down. The more carbon we put into the atmosphere now, the more emissions will have to fall in the future in order to limit temperature increases. The carbon budget bears a particularly usurious form of interest, because carbon remains in the atmosphere for many years after it is emitted. Therefore, what we emit now affects the climate system long after emissions peak and begin to decline.

According to the IPCC and additional analyses, if the current rate of emissions continues, there is a 66 percent chance that the carbon budget for keeping the global average temperature increase to 1.5 degrees will be used up sometime in 2021. In other words, even if we stopped all emissions five years from now, we’d still have only two chances out of three to hit a 1.5-degree target. (If we loosen the target to 2 degrees, we have 20 to 30 years left to eliminate all emissions in order to have a 66 percent chance of success.)

The IPCC’s calculations are not an academic exercise; they are about devastating harm to billions of people and irreversible damage to the planet. Given the emissions path we’re on, the IPCC estimated in 2013 that the rise in sea level by 2100 is likely to be approximately three feet. New research since that report shows that prediction to be optimistic. Many scientists believe that much more dramatic increases are likely.


If sea level rise is just below three feet, by 2070 Kolkata could have 14 million people at risk; Mumbai, 11 million; Guangzhou, China, 10 million; Dhaka, Bangladesh, 11 million; and Ho Chi Minh City, 9 million. Even accepting the conservative IPCC figure, by 2100 the number of people in the world who today live on land that will be submerged or exposed to chronic flooding will be many times the number of refugees currently flooding into Europe.

That’s not the only damage. Climate change puts saltwater into freshwater aquifers, meaning that low-lying land that is not fully submerged can be deprived of drinking water and thus made uninhabitable. Add to that severe heat waves and global food insecurity. It is hard to imagine that a world order that is already fraying under the current refugee crisis could withstand events of this magnitude. Little wonder that the Department of Defense is seriously alarmed by the effects of climate change, which it calls a “threat multiplier.”

One further note of caution that might not have been necessary before Nov. 8: If we were to use all the fossil fuels extracted so far and those that could be extracted in the future with today’s technologies (but not necessarily at current prices), leading scientists and economists have estimated that the rise in temperature would be an unimaginable 8.8 degrees Celsius.

We are at the edge of a precipice, from which there may still be just enough time to step back. But the window is narrow and closing quickly. In light of the imperative to keep fossil fuels in the ground, a more apt metaphor may be: “When you find yourself in a hole, stop digging.”


Ann Berwick was Massachusetts’ undersecretary for energy and later headed the Department of Public Utilities in the Patrick administration.