Global warming

Average global temperatures from 2010 to 2019 compared to a baseline average from 1951 to 1978. Source: NASA.

Global warming is the ongoing rise of the average temperature of the Earth‘s climate system and has been demonstrated by direct temperature measurements and by measurements of various effects of the warming. It is a major aspect of climate change which, in addition to rising global surface temperatures, also includes its effects, such as changes in precipitation. While there have been prehistoric periods of global warming,  observed changes since the mid-20th century have been unprecedented in rate and scale.

Land surfaces are heating faster than the ocean surface, leading to heat waves, wildfires, and the expansion of deserts. Increasing atmospheric energy and rates of evaporation are causing more intense storms and weather extremes, damaging infrastructure and agriculture. Surface temperature increases are greatest in the Arctic, which have contributed to the retreat of glaciers, permafrost, and sea ice. Environmental impacts include the extinction or relocation of many species as their ecosystems change, most immediately in coral reefs, mountains, and the Arctic. Surface temperatures would stabilize and decline a little if emissions were cut off, but other impacts will continue for centuries, including rising sea levels from melting ice sheets, rising ocean temperatures, and ocean acidification from elevated levels of carbon dioxide.

Effects

Physical environment

The environmental effects of global warming are broad and far-reaching. They include effects on the oceans, ice, and weather and may occur gradually or rapidly. Evidence for these effects come from studying climate change in the past, modelling and modern observations. Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency. Extremely wet or dry events within the monsoon period have increased in India and East Asia. Various mechanisms have been identified that might explain extreme weather in mid-latitudes from the rapidly warming Arctic, such as the jet stream becoming more erratic. The maximum rainfall and wind speed from hurricanes and typhoons are likely increasing.

Global warming has led to decades of shrinking and thinning of the Arctic sea ice, making it vulnerable to atmospheric anomalies. Projections of declines in Arctic sea ice vary. While ice-free summers are expected to be rare at 1.5 °C (2.7 °F) degrees of warming, they are set to occur once every three to ten years at a warming level of 2.0 °C (3.6 °F),  increasing the ice–albedo feedback. Higher atmospheric CO2 concentrations have led to an increase in dissolved CO₂, which causes ocean acidification. Furthermore, oxygen levels decrease because oxygen is less soluble in warmer water, an effect known as ocean deoxygenation.

Biosphere

In terrestrial ecosystems, the earlier arrival of spring, as well as poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming. It is expected that most ecosystems will be affected by higher atmospheric CO₂ levels and higher global temperatures. Global warming has contributed to the expansion of drier climatic zones, such as, probably, the expansion of deserts in the subtropics. Without substantial actions to reduce the rate of global warming, land-based ecosystems risk major shifts in their composition and structure. Overall, it is expected that climate change will result in the extinction of many species and reduced diversity of ecosystems. Rising temperatures push bees to their physiological limits, and could cause the extinction of their populations.

     

Humans

The effects of climate change on human systems, mostly due to warming and shifts in precipitation, have been detected worldwide. The social impacts of climate change will be uneven across the world. All regions are at risk of experiencing negative impacts, with low-latitude, less developed areas facing the greatest risk. Global warming has likely already increased global economic inequality, and is projected to do so in the future. Regional impacts of climate change are now observable on all continents and across ocean regions. The Arctic, Africa, small islands, and Asian mega deltas are regions that are likely to be especially affected by future climate change. Many risks increase with higher magnitudes of global warming.

Food and water

Crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative. Global warming of around 4 °C relative to late 20th century levels could pose a large risk to global and regional food security. The impact of climate change on crop productivity for the four major crops was negative for wheat and maize, and neutral for soy and rice, in the years 1960–2013. Up to an additional 183 million people worldwide, particularly those with lower incomes, are at risk of hunger as a consequence of warming.

Livelihoods, industry, and infrastructure

In small islands and mega deltas, inundation from sea level rise is expected to threaten vital infrastructure and human settlements. This could lead to homelessness in countries with low-lying areas such as Bangladesh, as well as statelessness for populations in island nations, such as the Maldives and Tuvalu. Climate change can be an important driver of migration, both within and between countries.

The majority of severe impacts of climate change are expected in sub-Saharan Africa and South-East Asia, where existing poverty is exacerbated. Current inequalities between men and women, between rich and poor and between people of different ethnicity have been observed to worsen as a consequence of climate variability and climate change. Existing stresses include poverty, political conflicts, and ecosystem degradation. Regions may even become uninhabitable, with humidity and temperatures reaching levels too high for humans to survive. In June 2019, U.N. special rapporteur Philip Alston indicated that global warming could “push more than 120 million more people into poverty by 2030 and will have the most severe impact in poor countries, regions, and the places poor people live and work”.

Health and security

Generally, impacts on public health will be more negative than positive. Impacts include the direct effects of extreme weather, leading to injury and loss of life; and indirect effects, such as undernutrition brought on by crop failures. Various infectious diseases are more easily transmitted in a warming climate, such as dengue fever, which affects children most severely, and malaria. Young children are further the most vulnerable to food shortages, and together with older people to extreme heat. Temperature rise has been connected to increased numbers of suicides. Climate change has been linked to an increase in violent conflict by amplifying poverty and economic shocks, which are well-documented drivers of these conflicts Links have been made between a wide range of violent behavior including fist fights, violent crimes, civil unrest, and wars.

       

How to stop global warming?

1. Renewable energies

The first way to prevent climate change is to move away from fossil fuels. What are the alternatives? Renewable energies like solar, wind, biomass and geothermal.

2. Energy & water efficiency

Producing clean energy is essential, but reducing our consumption of energy and water by using more efficient devices (e.g. LED light bulbs, innovative shower systems) is less costly and equally important.

3. Sustainable transportation

Promoting public transportation, carpooling, but also electric and hydrogen mobility, can definitely help reduce CO₂ emissions and thus fight global warming.

4. Sustainable infrastructure

In order to reduce the CO₂ emissions from buildings – caused by heating, air conditioning, hot water or lighting – it is necessary both to build new low energy buildings, and to renovate the existing constructions.

5. Sustainable agriculture & forest management

Encouraging better use of natural resources, stopping massive deforestation as well as making agriculture greener and more efficient should also be a priority.

6. Responsible consumption & recycling

Adopting responsible consumption habits is crucial, be it regarding food (particularly meat), clothing, cosmetics or cleaning products. Last but not least, recycling is an absolute necessity for dealing with waste.