It’s true that throughout earth’s 4.5-billion-year history, the climate has changed a lot. What is different is the dramatic and unprecedented scale of climate change. The rate of temperature rise is at least 10 times faster than that of the last mass extinction about 56 million years ago, when 95% of marine and 70% of land species were wiped out.
NASA has compiled a scientifically evaluated and compelling list of evidence for rapid climate change. This includes:
Global temperature rise
The planet’s average surface temperature has risen about 1.1 degrees Celsius (°C) – 2 degrees Fahrenheit (°F) – since the late 19th century. Most of the warming occurred in the past 40 years.
Rising ocean levels
Rising temperatures are causing glaciers and ice sheets to melt, adding more water to the oceans and causing the sea level to rise. Oceans absorb 90% of the extra heat from global warming; warmer water expands and so our oceans are taking up more space.
Warming ocean
The ocean has absorbed much of this increased heat, with the top 100 meters (about 328 feet) of ocean showing warming of more than 0.33°C (0.6°F) since 1969.
Shrinking ice sheets
Greenland lost an average of 279 billion tons of ice per year between 1993 and 2019, while Antarctica lost about 148 billion tons of ice per year.
Glacial retreat
Glaciers are retreating almost everywhere around the world, including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa.
Decreased snow cover
Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and the snow is melting earlier.
Sea level rise
Global sea levels rose about 8 inches (20 centimetres) in the last century. The rate in the last two decades, however, is nearly double that of the last century and accelerating slightly every year.
Extreme weather events
Since 1950, the number of record high temperature events worldwide has been increasing, while the number of record low temperature events has been decreasing. Climate change is causing many extreme weather events to become more intense and frequent, such as heatwaves, droughts, forest fires and floods.
The scientific evidence that climate change is a real, present threat is undeniable.