This article was originally published in 2009 and has been updated.

By now most of us have heard the statistics. If we don’t limit our planet’s warming to 1.5 degrees above pre-industrial levels, we will set in motion cataclysmic change that will result in lost ecosystems and irreversible damage to our planet.

Some of these changes are already occurring.

The last 40 years have seen the warmest surface temperatures in recorded history. The past several years have been among the warmest on record. Spring of 2019 set a record for the highest amount of carbon dioxide in the atmosphere in 800,000 years.

Scientists have concluded that human activity, primarily the burning of fossil fuels, is the major driving factor in climate change. According to the National Oceanic and Atmospheric Administration (NOAA), “Fossil fuels like coal and oil contain carbon that plants pulled out of the atmosphere by photosynthesis over the span of many millions of years; we are returning that carbon to the atmosphere in just a few hundred years.”