Menu
Multiple analyses of the peer-reviewed science literature have repeatedly shown that more than 97% of scientists in this field agree that the world is unequivocally warming and that human activity is the primary cause of the warming experienced over the past 50 years. Spirited debates on some details of climate science continue, but these fundamental conclusions are not in dispute.
Many lines of evidence demonstrate that human activities are primarily responsible for recent climate changes. First, basic physics dictates that increasing the concentration of CO2 and other heat-trapping gases in the atmosphere will cause the climate to warm. Second, modeling studies show that when human influences are removed from the equation, climate would actually have cooled slightly over the past half century. And third, the pattern of warming through the layers of atmosphere demonstrates that human-induced heat-trapping gases are responsible, rather than some natural change.
“Global warming” refers to the long-term warming of the planet. “Climate change” encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.
The reason heat-trapping gases like carbon dioxide, methane, and nitrous oxide have such a powerful influence on Earth’s climate is their potency: although they are transparent to visible and ultraviolet solar energy, allowing the sun’s energy to come in, they are very strong absorbers of the Earth’s infrared heat energy, blanketing the Earth and preventing some of the energy to escape to space.
The oceans cover more than two-thirds of the Earth’s surface and play a very important role in regulating the Earth’s climate and in climate change. Today, the world’s oceans absorb more than 90% of the heat trapped by increasing levels of carbon dioxide and other greenhouse gases in the atmosphere due to human activities. This extra energy warms the ocean, causing it to expand. This in turn causes sea level to rise. Of the global rise in sea level observed over the last 35 years, about 40% is due to this warming of the water. Most of the rest is due to the melting of glaciers and ice sheets. Ocean levels are projected to rise another 1 to 4 feet over this century, with the precise number largely depending on the amount of global temperature rise and polar ice sheet melt.
As human-induced emissions of carbon dioxide build up in the atmosphere, excess carbon dioxide dissolves into the oceans, where it reacts with seawater to form carbonic acid, which makes ocean waters more acidic and corrosive. These changes to ocean chemistry can affect many living things, and possibly the entire food web.
Yes, the ocean is continuing to warm. Notably, all ocean basins have been experiencing significant warming since 1998, with more heat being transferred deeper into the ocean since 1990.
While we can’t stop climate change in its tracks, we can limit it to less dangerous levels by reducing our emissions. Even if all human-related emissions of carbon dioxide and the other heat-trapping gases were to stop today, Earth’s temperature would continue to rise for a number of decades and then slowly begin to decline. However, focusing on short-lived types of emissions, such as methane and black carbon (soot), can reduce the rate of change in the near term. Because of the complex processes controlling carbon dioxide concentrations in the atmosphere, even after more than a thousand years, the global temperature would still be higher than it was in the pre-industrial period. As a result, without technological intervention, it will not be possible to totally reverse climate change. We do face a choice between a little more warming and lot more warming, however. The amount of future warming will depend on our future emissions.