The pandemic has shaken much of human society, but still the threat posed by global warming has not gone away. The Earth's average temperature is about 15 °C, in recent years the temperature has been much higher and lower. There are natural fluctuations in the climate, but scientists say temperatures are now rising faster than at many other times. The planet's average surface temperature has gone up about 2.12 °F, that is 1.18 °C since the late 19th century. This change was driven largely due to increased carbon dioxide emissions into the atmosphere, and other human activities. Most of the warming occurred in the past 40 years, with the seven most recent years being the warmest. The years 2016 and 2020 are tied for the warmest year on record. Human activities have increased carbon dioxide emissions which resulted in driving up temperatures. Extreme weather and melting polar ice are among the possible effects. Most man-made emissions of carbon dioxide come from burning fossil fuels. When carbon absorbing forests are cut down and left to rot or burned, the stored carbon is released and it contributes to global warming. Fossil fuel burning for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and manufacturing. The ocean has absorbed much of this increased heat, with the top 100 meters of ocean shows the warming of more than 0.33 °C since 1969. Earth stores 90% of the extra energy in the ocean. Temperature rise is amplified in the Arctic, where it has contributed to melting permafrost, glacial retreat and sea ice loss. Warmer temperatures are increasing rates of evaporation, causing more intense storms and weather extremes. Solar energy radiating back to space from the Earth's surface is absorbed by greenhouse gases and re-emitted in all directions. This heats both the lower atmosphere and the surface of the planet. Without this effect, the Earth would be about 30 °C colder and hostile to life. Across the globe, the average sea level increased by 3.6 mm per year between 2005 and 2015. Most of this change was because water increases in volume as it heats up, however, melting ice is now thought to be the main reason for rising sea levels. Most glaciers in temperate regions of the world are retreating. The satellite records show a dramatic decline in Arctic sea ice since 1979. The Greenland ice sheet has experienced a greater record of ice melting in recent years. Satellite data also shows the West Antarctic ice sheet is losing mass. A recent study indicated East Antarctica may also have started to lose mass. The effects of a changing climate can also be seen in vegetation and land animals. These include earlier flowering and fruiting times for plants and changes in the territories of animals. The WMO says that if the current warming trend continues, temperatures could rise 3 to 5 °C by the end of this century. The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost an average of 279 billion tonnes of ice per year between 1993 and 2019, while Antarctica lost about 148 billion tonnes of ice per year. A new study by NASA and university researchers has found that the ocean waters melting the undersides of Antarctic ice shelves are responsible for most of the continents' ice shelf-loss. There is a severe impact on ecosystems, which include the relocation or extinction of many species as their environment changes, most immediately in coral reefs, mountains, and the Arctic. Climate change threatens people with food insecurity, water scarcity, flooding, infectious diseases, extreme heat, economic losses, and displacement. These impacts have led the World Health Organization to call climate change the greatest threat to global health in the 21st century. Even if efforts to minimize future warming are successful, some effects will continue for centuries, including rising sea levels, rising ocean temperatures, and ocean acidification. Recent warming has driven many terrestrial and freshwater species moved towards the poles and higher altitudes. Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics. The size and speed of global warming is making abrupt changes in ecosystems more likely. Overall, it is expected that climate change will result in the extinction of many species. Heat waves in the ocean occur more frequently due to climate change, with harmful effects found on a wide range of organisms such as corals, kelp, and seabirds. Ocean acidification is impacting organisms who produce shells and skeletons. Coral reefs have seen extensive bleaching after heat waves. Global climate is projected to continue to change over this century and beyond. The intensity, frequency, and duration of the strongest hurricanes have all increased since the early 1980s. In the next several decades, storm surges and high tides could combine with sea level rise, and land subsidence to further increase flooding in many regions. Ocean waters will therefore continue to warm and sea level will continue to rise for many centuries. The Arctic Ocean is expected to become essentially ice-free in summer, before mid-century. China is responsible for around 28% of global greenhouse gas emissions. Countries have only a limited time, they have already signing up to deep carbon cuts and there has already been progress. China aimed to go carbon neutral by 2060. The European Union followed suit in March 2020. Since then, Japan and South Korea have joined the cause. What the UN estimates is now a total of over 110 countries that have set net zero target for mid-century. Citizens and governments can choose among several options, they can change their pattern of energy production and usage in order to limit emissions of greenhouse gases. Renewables are now the cheapest energy ever. Renewables are already often cheaper than fossil fuel power in much of the world when it comes to building new power stations. While our understanding of how climate change affects, whether is still developing, evidence suggests that extreme weather may be affected even more than anticipated. Extreme weather is on the rise and the indications that it will continue to increase in both predictable and unpredictable ways.