We compare the negative effects of global warming and climate change, such as  global health issues, melting ice caps, sea levels rising, desertification, extinction of species, and natural disasters. 

The politics of climate change

President Donald Trump announced that the USA was pulling out of the Paris Agreement on climate change. This controversial decision triggered immediate responses from world leaders, such as Emmanuel Macron and Vladimir Putin, and prominent figures in the scientific community. Trump's decision may jeopardize the future of the planet, as some of the policies for mitigation of global warming should be implemented immediately if we want to avoid an increase in average temperatures which may bring catastrophic environmental consequences. The problem of climate change is that countries have the temptation to "free-ride" on the efforts of others to reduce emissions. In the past, developed countries have led the process as they were those with more capacity to make the investments and sacrifices required to curb emissions. However, if the USA, which is the country with the greatest historical responsibility in terms of greenhouse emissions (highest accumulated emissions) decides to stop contributing to the effort to fight climate change, other countries may follow their example and also renege on their commitment to the Paris Agreement.

If political leaders continue prioritizing the short-term interests of their countries and postponing action against global warming and other environmental problems, future generations will see their life conditions worsen dramatically. There is a tension here between short-term economic angle and long-run social and ethical considerations. Even the economic sustainability of the world may be endanger if average temperatures continue to increase triggering many other negative effects on our planet. Here we discuss the harmful consequences of global warming.

Negative effects of global warming

Among the academic community, there is little doubt that fossil fuels are contributing to global warming and climate change. Energy is a requirement for economic progress, and so far fossil fuels have been the main source of energy in most economies. Economic and population growth have contributed to increasing emissions of green-house gases (GHG), including, carbon dioxide (CO2) and chlorofluorocarbons (CFCs), which have led to unprecendented concentration levels of these gases in the atmosphere. Scientists link the concentrations of GHG in the atmosphere with the changes in climate trends recently observed, and, in particular, with the increase in average temperatures on Earth.

Scientists disagree nonetheless on the severity of the consequences of climate chage. What possible effects of global climate change should we be most concerned about? This is a list of the most notable dangers associated with climate change:

• Human health threat: Climate change as been described as "the biggest global health threat of the 21st century". The Lancet / UCL commission on health and climate change estimates that a 4°C increase in temperatures, which is a probable outcome given the current trends in CO2 concentration, would have very serious and potentially catastrophic effects for human health and survival. Many consequences of climate change will directly or indirectly provoke global health issues, such as spread of infectious diseases like malaria, malnutrition, heatstrokes, insufficient sanitation, access to drinking water and secure shelter.
• Melting ice caps and rising sea levels: the melting of glaciers and ice sheets due to global warming is extremely problematic. These cover about 10% of the world's land and hold approximately 75% of fresh water. Meltbacks of glaciers in Alaska, Himalayas, Andes and even Kilimanjaro in Africa are well documented. The loss of glaciers can produce water shortages for irrigation and consumption and limit hydropower. The loss of ice mass in Greenland and Antarctica will produce a sea level rise affecting world coastal areas and forcing mass migrations. Moreover, fresh melt water can impact thermohaline circulation and salinity levels, altering marine ecosystems.
• Desertification: global warming have a serious impact on drylands. The expected rise of temperatures by 2°C to 5°C will raise the rate of evapo-transpiration, and decrease soil humidity. Fires and floods are also causes of desertification. Deserts may grow and rivers run dry in arid regions. Crops would be hurt and populations, which are already vulnerable, hit. Many species would see their habitat threatened as a result of desertification.
• Extinction of species: many plants and animal species would dissapear as a consequence of global warming. Wildlife is impacted directly and indirectly by climate change. A sixth of the Earth's species could be heading towards extinction according to some experts. In particular, endemic species and those with limited ranges or high specialization could disappear at unprecedented rates. Forced migrations, changes in temperatures, lack of food, natural disasters, and rise of sea levels are among the propiciatory factors of extinction processes.
• Natural disasters: extreme weather events are among the most commonly argued negative effects of climate change. Floods, wildfires, tropical cyclones and extreme hot days would arguably become more common if the average temperature of Earth continues to rise. Natural disasters are extremely costly. Many human lives would be lost and the damage to the environment would also be severe and long lasting.
• Other consequences: there are several other negative effects of global warming and climate change, such as ocean acidification, economic losses, political conflicts for scarce resources, plagues, and changes in ecosystems.

The above-mentioned negative consequences of climate change are to a great extent interconnected. Some of them exacerbate the effects of others. We invite you to share with us which of these problems you find the most concerning.

Videos: Intergovernmental Panel on Climate Change (IPCC) and interview to Professor Hugh Montgomery (UCL)
 

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