Scientific Evidence on Climate Change

Tropical Landscape, Natalya Critchley

There is a strong consensus among scientists that climate change is real and that it is caused by human activities. The Intergovernmental Panel on Climate Change (IPCC), the leading international body for the assessment of climate change, has concluded that it is extremely likely that human activities caused more than half of the observed increase in global mean surface temperature from 1951 to 2010.

There are several lines of evidence that support this conclusion. One of them is the increase in the concentration of greenhouse gases in the atmosphere. Greenhouse gases trap heat in the atmosphere causing the planet to warm. The concentration of greenhouse gases in the atmosphere has been increasing since the Industrial Revolution, and this increase is largely due to human activities such as the burning of fossil fuels.

Another line of evidence is the observed changes in the Earth’s climate system. These changes include rising global temperatures, melting glaciers, rising sea levels, and an excess of extreme weather events. These changes are consistent with the predictions of climate models that take into account the observed increase in greenhouse gas concentrations.

The evidence that climate change is due to human activities is overwhelming. It is important to take action to reduce greenhouse gas emissions and to mitigate the effects of climate change.

There is a vast body of scientific evidence that shows that climate change is real and that it is caused by human activity. This evidence includes:

Rising global temperatures. The average global temperature has increased by about 1 degree Celsius since the late 19th century. This warming is most pronounced in the Arctic where temperatures have increased by about 2 degrees Celsius.
Melting glaciers and ice sheets. Glaciers and ice sheets are melting at an accelerated rate. Since 1961, the Greenland ice sheet has lost about 267 billion tons of ice per year, and the Antarctic ice sheet has lost about 152 billion tons of ice per year. Glaciers provide a vital source of freshwater for millions of people, and their loss could have severe consequences.
Rising sea levels. Sea levels have risen by about 8 inches since 1880. This rise is due to both the melting of glaciers and ice sheets, and the expansion of water as it warms.
Ocean acidification. The ocean has absorbed about 30% of the carbon dioxide (CO₂) emitted by human activities since the Industrial Revolution. This has caused the ocean’s pH level to decrease by about 0.1, making it more acidic. This acidification can harm marine life and disrupt entire ocean ecosystems.
More extreme weather events. Climate change is causing more extreme weather events such as heat waves, droughts, floods, and hurricanes. These events are becoming more frequent and more severe.
Changes in plant and animal life. Climate change is causing changes in plant and animal life, particularly the timing of seasonal events such as the blooming of flowers and the migration of birds. Many species are moving to higher latitudes or altitudes in order to find cooler temperatures. Some species are becoming extinct, while others are adapting to the changing climate.

There have been numerous research studies that provide solid evidence of climate change. Here are a few examples:

A study published in the journal Science in 2013 analyzed temperature records from the past 11,000 years and found that the current warming trend is unprecedented in that time period. The study concluded that the warming is most likely caused by human activities.
Another study published in the journal Nature in 2016 used satellite data to show that the Earth’s land areas have become greener in recent decades, likely due to rising carbon dioxide levels. However, the study also found that this greening effect may be temporary and could eventually be reversed by other effects of climate change.
A s tudy published in the journal Nature Climate Change in 2018 used climate models to project future changes in extreme weather events. The study found that heatwaves, droughts, and floods will become more frequent and severe in many parts of the world due to climate change.
A report published by the Intergovernmental Panel on Climate Change (IPCC) in 2018 analyzed thousands of research papers on climate change and concluded that human activities, such as burning fossil fuels and deforestation, are the primary cause of the warming trend observed over the past century.
A study published in the journal Nature in 2018 used satellite data to show that the world’s oceans have absorbed much more heat than previously estimated. The study found that the oceans have absorbed about 90% of the excess heat trapped by greenhouse gases, which has led to sea level rise and other impacts.
The report by the IPCC of 2021 details the regional extent of the climate change regarding intense floods and droughts, distorted rainfall patterns, continued sea level rise, further permafrost thawing and glacier melting, and changes in the marine ecosystems due to heatwaves, ocean acidification, and reduced oxygen levels.
According to NOAA scientists, the levels of the three main greenhouse gases ̶ carbon dioxide, methane, and nitrous oxide ̶ continued to grow in the atmosphere at historical high rates during 2022.
A recent study published in the journal Earth System Science Data in 2023 concluded that during 2013-2022 human-induced warming has been increasing at a rate of more than 0.2^oC per decade. This unprecedented high rate is the result of a combination of greenhouse gas emissions and reductions in aerosol-cooling strength.
A predicted fingerprint of the human-driven climate change ̶ as the level of carbon dioxide rises, the lower part of the atmosphere gets hotter while the upper part gets colder ̶ has been confirmed in a study published in PNAS in 2023.

These are just a few examples of the many research studies that have provided solid evidence of climate change. The scientific consensus on this issue is clear: the Earth’s climate is changing, and human activities are the primary cause.

How much difference can one degree of warming make?

Revealed: the huge climate impact of the middle classes

Richest 1% account for more carbon emissions than poorest 66%, report says

New Research Sparks Concerns That Ocean Circulation Will Collapse

The Upper Atmosphere Is Cooling, Prompting New Climate Concerns

World likely to breach 1.5C climate threshold by 2027, scientists warn

Tropical forests are approaching critical temperature thresholds

Climate change likely led to violence in early Andean populations

Tracking the accelerated meting of glaciers in Greenland