The Earth's climate has changed many times in the past, resulting in shifts in temperature and sea level. Scientists have linked recent global warming to human activities, especially the burning of fossil fuels. A group called IPCC was formed to study climate change and its effects due to greenhouse gas emissions. Their research shows that global temperatures have risen by about 0.6 degrees Celsius in the last century. If we keep emitting greenhouse gases, temperatures could increase by as much as 5.8 degrees Celsius by 2100. This could lead to melting glaciers, rising sea levels, and threatened islands and coastal cities. Some scientists question the accuracy of the IPCC's findings, suggesting that the claims of significant global warming may be exaggerated or incorrect, based on computer models rather than solid evidence.