Although there are many causes of climate change, human activities, without any doubt, still plays a significant role in it. As a matter of fact, 20th Century is the warmest ten years in the past decades, and the 2001-10 period was the warmest since modern instrumental records began. Global climate change will bring incalculable losses to human beings, and the idea that climate change makes human beings pay a huge price is widely accepted by the world.it already becomes a global environmental problem that is widely concerned and studied. This essay will discuss the source and cause of climate change caused by human, the impact of climate change on the environment, and the solution to climate change.

The Intergovernmental Panel on Climate Change (IPCC) in its fourth assessment report pointed out that human activity is likely to be the major cause of global warming since the second half of the 20th century, (Smith, Schneider, Stephen and Oppenheimer, 2009) but indeed, Human-caused global warming actually occurred earlier. Since it is rare to directly measure climate before 1900, human-induced climate change is often referred to as the phenomenon of the 20th century. An international research project found that human activity has caused nearly two centuries of global warming, much earlier than scientists had expected, proving that human-induced climate change is not only a phenomenon of the 20th century. The study notes that global warming began in the early stages of the industrial revolution, first discovered in the Arctic and tropical oceans around 1830 (Humans have caused climate change for 180 years).

According to the report above, human impacts on climate change started a long time ago and have reached a severe level until now. The fifth report of IPCC(AR5) has provided a set of data proving the human impact on climate change. The most direct evidence of human influence to the climate change is the change of global average surface temperature. 1880 ~ 2012, the global average surface temperature increased by 0.85 ℃; 1951 ~ 2012, the global average surface temperature of the heating rate is 0.12 ℃ / 10 years, the heating rate is almost two times as much as the data of 1880-1950 (AR5). The past 30 years have been warmer than any decade since 1850. At the same time, the data on Marine thermal content and radiation compulsion is also very exaggerated.1971~2010, the upper level of the ocean (0~700 meters) heat content increased by about 17 x J(AR5), the maximum temperature is almost near the ocean surface.1750~2011, total radiation compulsion is 2.29W/m2(AR5), which is 43% higher than the artificial radiation forced value of 1.6 W/m2 calculated by AR4 in 2005, more than 40 times higher than the radiation forced 0.05 W/m2 generated by the change of solar irradiance in the natural factors. The data indicate that Climate change has been very intense in recent years due to the rapid development of human society.

The most important cause of the temperature change is the increase in greenhouse gas emissions. AR5 has quantitatively attributed the temperature changes in recent 60 years. 1951~2010, the rise of global average surface temperature caused by greenhouse gases is between 0.5 and 1.3 degrees C(AR5). These data indicate that greenhouse gas emissions have a great impact on climate change, and the use of fossil fuels plays an important role in the rise of greenhouse gas emissions. Since the industrial revolution of human society in 1750, The concentration of carbon dioxide, CH4 and N2O and other greenhouse gases in the global atmosphere continues to rise. the increase of greenhouse gas concentration since industrialization was mainly caused by the use of fossil fuel, the CO2 of fossil fuel combustion and cement production has reached 3750 tons of carbon in the atmosphere(AR5). “It (fossil fuel)is the direct contributor to climate changes by emitting large amounts of greenhouse gases, such as carbon dioxide, methane, sulfur dioxide and nitrogen dioxide” (Climate Change Caused by Human）.Fossil fuels also release carbon particles that influence the atmosphere. Carbon particles produced by burning fossil fuels increase the density of the atmosphere, causing the sun’s heat radiation to be absorbed and preserved inside the earth without being released, which Cause the earth to slowly warm up.

The destruction of the environment is also responsible to the climate change. “The second type of human impact, the conversion of vegetation by deforestation, afforestation, and agriculture, is identifiers mounting attention as a further source of climate change”（Stephen T. Jackson）. Due to the increase in the population of the world, Urban expansion and increased demand for agricultural products have led to extensive deforestation. The forest soil is relatively moist, but without the protection of trees, the moisture in the soil will evaporate quickly. Trees also send water vapor into the air to accelerate the water circulation. Deforestation will weaken the cycle, and many forests will turn into deserts with the disappearance of trees. Deforestation will deprive the forest of protection. Trees will block sunlight during the day and maintain the temperature at night. Deforestation can cause severe temperature fluctuations, which could bring tons of damage to plants and animals. Trees can also absorb a large amount of carbon dioxide that contribute to global warming. The land destruction caused by vegetation and other land use change is estimated to have released 18 tons of carbon dioxide emissions(AR5), The reduction of forests means more greenhouse gases are released into the air, and the pace and extent of global warming will not be alleviated.

The huge increase in population in recent years is another one of the important causes of global warming. “for each 1 percent increase in population, there will be a bit more than a 1% increase in greenhouse emissions” (Eugene A. Rosa & Thomas Dietz). Such a large population emits an alarming amount of carbon dioxide each year. It would lead to a direct result of increased carbon dioxide in the atmosphere. Meanwhile, it also seriously affects the balance of the natural ecological environment. which has already been mentioned above.
The discharge of wastewater can also cause climate change. The entry of industrial wastewater into the ocean will cause the increase in ocean temperature, abnormal ocean currents, and regional climate change. At the same time, the ocean is dominant in the energy storage of the climate system. the ocean absorbs tons of carbon in the artificial CO2, causing severe acidification of the sea surface water, which will have an impact on the marine ecosystem.

Climate change has had a very serious impact on the environment, such as the change in the water cycle, the rise of sea level, the shrinking of the arctic circle, and the change of extreme events. The rise of global temperature will increase the temperature of the sea water, which will cause the sea water to expand and the sea level to rise. 1901~2010, due to thermal expansion of seawater, ice and terrestrial water storage into the ocean, the global sea level rise of 0.19 meters, the average increase rate of 1.7mm/ years(AR5), which is the highest over the past two thousand years. If the problem is not alleviated, coastal areas will be destroyed by salt tide or even be submerged. The unnatural snow and ice reduction caused by climate change also influenced the rise of the sea level, and it is a long-term hidden danger to freshwater resources. From 1967 to 2012, spring snow cover in the northern hemisphere shrank 1.6 percent every ten years. Between 1971 and 2009, global mountain glaciers reduced ice volume by an average of 226 billion tons per year. From 1979 to 2012, Arctic sea ice shrank by 3.5 to 4.1 percent every ten years. Between 2002 and 2011, Greenland’s ice sheet lost about 215 billion tons of ice each year, while the Antarctic ice sheet lost about 147 billion tons each year(AR5). Climate change also caused environmental changes in different latitudes–global desertification, forest area reduction, grassland expansion and so on, extreme weather and climate disasters such as heat waves, drought, rainstorms, typhoons and so on are becoming more frequent. These changes not only have great effects on animals and plants, but also human beings ourselves. Agriculture and natural ecosystems cannot quickly adapt to this change, resulting in a large range of forest vegetation destruction and agricultural disasters. The food production decreased, millions of people facing the threat of hunger. Climate warming is likely to increase disease risk and mortality. The high temperature will increase the burden of the human circulation system, and heat waves will cause an increase in the risk of disease mortality. The global number of deaths due to climate change leading to diarrhea, malaria, and malnutrition is up to 150 thousand people per year, and the number is estimated to increase to 300 thousand in 2020(AR5). At present, the whole world is faced with the problem of exhaustion of resources, unbearable environmental carrying capacity, and the fragile ability to respond to natural risks, climate change makes these problems even more serious.

At the same time, the fifth report of IPCC also predicted future climate change. Compared with the data from 1986-2005, it is estimated that the global average surface temperature will increase by 0.3 to 0.7 degrees in 2016-2035, and 0.3 to 4.8 degrees in 2081-2100. Under the premise of future global warming, extreme warming events will further increase, and extreme cold events will be further reduced. The frequency of heat waves will be higher and longer. The intensity of heavy rainfall in most of the middle latitudes and in the humid tropical regions may increase, and the frequency may increase, and the global precipitation will show a trend of ” drought and waterlogging.” The Arctic sea ice will continue to melt. The global glacier volume and the snow cover in the northern hemisphere will also decrease, and the global sea level will rise further. By the end of the Twenty-first Century, the Arctic sea ice range will be reduced by 43% to 94% in September, 8% to 34% in February, 15% to 85% in the global glacier volume, 7% to 25% in the northern hemisphere and 0.26 to 0.82 meters in the global sea level(AR5). If the climate change plan cannot be solved as soon as possible, the climate problem will become impossible to solve.

It is imminent to solve the problem of climate change. According to the fifth assessment report (AR5) of the IPCC, more than half of the global warming since the 1950s is caused by human activities (more than 95% probability), human beings need to be responsible for the environment. Because of the climate change caused by mankind, the living environment of mankind has also been seriously affected. The rise of sea level, the aggravation of water pollution, the increase of agricultural production cost and so on will be borne by mankind itself. At the same time, the climate change caused by human beings can only be solved by human beings. To reduce the impact of mankind on climate change, the most direct way is to reduce the emissions of greenhouse gases. To achieve this goal, improving energy utilization is the very first step that needs to be done, along with the development of renewable energy and replacing energy, a large part of the problem will be solved. For CO2, which has already been discharged into the atmosphere, what we can do is to separate it from recycling. According to the present research results, what human beings can do now is to develop high carbon energy, high carbon fertilizer, hydrate technology and greenhouse gas treatment. In order to speed up the process, strengthening international cooperation in technology and funds is also very important. And in nature, we can do a lot of work, the most important of which is to protect the environment. The most practical way is to plant trees widely and stop deforestation, to take industrial production activities under control, and for each one of us, to pay attention to every small thing that we can do for the environment, such as using public transport and energy-efficient appliances. It is urgent to protect the environment not only for the present but also for the future. Only by reducing the impact of human on the environment can make the survival of human beings and all species living on the earth better.