Dan Lashof, Program Director, Climate & Clean Air, Washington, D.C.
Research recently published in the scientific journal Nature is receiving a lot of attention, and for good reason. It puts a specific date – 2047 – on when we will be living in a new world due to unlimited dumping of heat-trapping pollution into our atmosphere.
From this date onward the researchers project that every subsequent year will be warmer than any year in the historical record (1860 to 2005) for more than half the locations on earth. Think about that for a minute. It means that well within my children’s lifetime they will be living in a climate that, despite natural variability, has no overlap with the climate when they were born. That’s why I call it a new world.
Here is the key figure from the paper (as reformatted on the author’s website):
This is actually a very conservative definition of a new world. The historical record has already been significantly affected by carbon pollution. If that were not the case the warmest year in the historic record would be significantly cooler and the departure date from the historical range would come 11.5 years sooner, or in 2036, according to the paper.
The other key finding of Mora et al. is that the new world will begin sooner in the tropics than at higher latitudes. This may seem surprising because global warming (measured as the absolute change in temperature) is taking place faster toward the poles. But natural variability is also much greater outside the tropics, so measuring global warming relative to the historical range of temperatures at a given location changes the picture. For example, while New Yorkers will experience a completely new climate by 2047 (the same as the global average), residents of Kingston, Jamaica will be living in a new world by 2023. What this means is that people with the fewest resources, who are concentrated in the tropics, will face unprecedented climatic conditions soonest.
Results for many cities around the world are provided on the author’s web site. Here are the departure dates for the U.S. cities listed, assuming unabated carbon pollution.
These projections are not destiny. Mora et al. also looked at a scenario in which heat-trapping pollution is stabilized at a level equivalent to doubling the preindustrial concentration of carbon dioxide and found that the departure date was delayed until 2069. That would buy some time for people and ecosystems to try to adapt, but it would still mean bequeathing our children a fundamentally disrupted climate.
We can and must do better.