"Scientific evidence for warming of the climate system is unequivocal."
- Intergovernmental Panel on Climate Change
The Earth is warming, not the Sun
We know that the Earth is warming from the other pieces of evidence I will mention. But in my opinion, this is the most proving piece of evidence. Climate change has happened in the past, before human impact, and that has been a big point for climate deniers. This has been due to increases of the Sun's intensity. However the latest climate change we know is because of human impact, and not an increase in the Sun's intensity. We know this because if the Sun's intensity increased, we would see increases in heat from all parts of the atmosphere. However, only the lower part of the atmosphere is warming, caused by human impact. In fact, the upper part of the atmosphere is cooling, possibly because of the sunlight not coming back out of the lower part of the atmosphere due to the greenhouse effect. Therefore, the increase in temperature is not being caused by the Sun.
400 PPM - And It's Us
This piece of evidence is pretty straight forward. 400 PPM stands for 400 parts per million of carbon dioxide.
Before the 18th century, when humans in the industrial revolution began to burn coal, oil and gas, our atmosphere typically contained about 280 parts per million of carbon dioxide. Those are the conditions on which civilization developed and to which life on earth is adapted.
Now, as the use of fossil fuels spreads through the world, the amount of carbon in the atmosphere is skyrocketing — we’re now well over 400 parts per million CO2 in the atmosphere.
We need to get back below 350 parts per million if we want this Earth to survive. Because 65% of carbon dioxide released at any given moment is taken away from the atmosphere in about 200 years, if we stop using fossil fuels and other causes of climate change, then there is a large possibility that we will get back below 350 PPM within the next few centuries. However, if we keep using the causes of climate change, then climate change will just keep getting worse, bringing the effects along with it.
The next graph gives a zoomed in view of the past 13 years.
Global temperatures are going up
The global temperatures have been proven to be going up. The planet's average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. There has been an increase of 1.8ºF since the early 20th century. Most of the warming occurred in the past 35 years, with 16 of the 17 warmest years on record occurring since 2001. Not only was 2016 the warmest year on record, but eight of the 12 months that make up the year — from January through September, with the exception of June — were the warmest on record for those respective months. This evidence has all been proven by NASA's satellites.
The ice caps are obviously melting
As you know, an effect of climate change is that the polar ice caps are melting (if you do not, click here). The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005.
Decreased Snow Cover
Relating to the fact that the ice caps are melting, there has been decreased snow cover in areas all over the country. NASA satellite observations have discovered that the amount of snow cover has been rapidly decreasing over the last 50 years, as well as the earlier snowmelt time. This is caused by climate change because of the warming temperatures I have previously spoken of. The graph earlier on this page shows how there has been a recent significant increase in the amount of carbon dioxide in the air. The last 50-60 years, to be precise. We are getting high above the 400 PPM mark that I talked about earlier. This is therefore clear evidence of the effects of climate change on snow. Personally, I can see this happening in my home town of New York City. We have been getting less and less snow and it is staying for less time on the rooftops. This means that in recent years, there has been more heat as a result of climate change.
Warming Ocean and Rising Sea Levels
As proven earlier on this page, the temperature is warming. When the temperature of the atmosphere warms, it also warms something else: the oceans. Oceans have been proven to be warming in the last half-century. Oceans absorb heat from the atmosphere. Therefore, on a warming planet, the oceans would be warming. Data, acquired from NASA's satellites, shows that the top 700 meters of the ocean (about 2,300 feet) show warming temperatures of about 0.302 degrees Fahrenheit since 1969.
In addition, it has also been proven that sea levels have been rising. Data from the IPCC working with the CSRIO Marine and Atmospheric Research shows that there has been a 9.5-inch sea level rise in the past century. This next graph shows the sea level rise from 1880 to 2013.
The next graph shows the sea level rise measured directly from NASA's satellites since 1993. Please note that both sources are credible, but this next graph is more up-to-date and slightly more accurate because it is measured with modern technology, whereas in 1880 they didn't have modern sea level records.
This NASA graph is updated every month, and those updates will also be on this site.