Greenhouse Gases 

Greenhouse gases such as carbon dioxide, methane, nitrous oxide and others, are a major contributor of rising temperatures. Concentrations of carbon dioxide in the atmosphere surpassed 400 parts per million in 2013. Likewise, methane and nitrous oxide concentrations are also breaking records.

These gases are released through human activities, and for the past four decades the majority of greenhouse gasses (78%) have come from industrial activity, the burning of fossil fuels for energy and livestock production.

The Enhanced Greenhouse Effect

Sunlight passes through the earth’s atmosphere and warms the surface of the earth. Most of this heat is radiated back upwards. Gases within the Earth’s atmosphere, including carbon based greenhouse gases like carbon dioxide and methane; serve to re-absorb a large percentage of this heat and radiate in all directions. This process is known as the greenhouse effect and ensures the earth’s surface is warmed to a life-supporting average of 15 degrees Celsius.

Human activities have contributed to the extensive release of carbon based emissions, nitrous oxides and chlorofluorocarbons (CFCs). The buildup of these long lived greenhouse gases in the atmosphere has resulted an enhanced greenhouse effect; that causes more heat to be trapped and retained within the atmosphere than usual – leading to a gradual but steady rise in global surface and lower-atmospheric temperatures

The difference between the greenhouse effect and an enhanced greenhouse effect is explained in the diagram below.

 The Albedo Effect

Albedo is the amount of light or radiation that is reflected from a surface. A surface with high albedo reflects most of the light/heat radiation and absorbs the rest, and vice versa. On Earth, the amount of light and heat reflected from the surface is a function of what is on our surface: forests, oceans, urban regions, deserts, and polar ice caps. As such changes in albedo contribute significantly to fluctuation in global temperature readings.

Source: https://newint.org/features/2009/07/01/arctic-climate/

Bright ice and snow (high albedo) reflect 95% of heat radiation. However, with rising global temperatures, snow and ice has been melting, thus reducing the albedo for the region as previously iced over areas turn into land or ocean. This leads to a spiraling cycle known as the ice-albedo feedback.

Similarly, the clearing of forest areas results in a short term cooling effect as more radiation is reflected back into the atmosphere from the bare surface. However, because clearing of forest involves biomass combustion (remember the annual haze?), large amounts of carbon dioxide are released into the atmosphere, enhancing the greenhouse effect and contributing to long term global warming.

The frequency of extreme weather events have increased rapidly over the last 50 years. According to the International Panel on Climate Change (IPCC) human activities have had large scale effects upon climate change and its associated frequency and intensity of extreme events (floods, droughts, heatwaves, bushfires, and storms). Weather related losses have increased massively worldwide, from $10 billion per annum (1974 – 1983) to a staggering $131 billion (2004 – 2013). 

Scientists have predicted that these changes are likely bring about non-linear responses that could further incite rapid climate change, drastic alterations in seasonal weather patterns, accelerated loss of polar ice caps, and even the collapse of the ocean circulation systems.

Source: Standard & Poor's (2014)

Scientific research has determined that the Global Mean Sea Level (GMSL) has risen by 10 – 20 cm in the last century. The average rate of rise over the last 20 years however has been an unprecedented 3.2 mm per annum, approximately twice the average speed of sea-level rise in the preceding 80 years.

Source: CSIRO (2016)

Global sea level rise has been tied to 3 primary factors – thermal expansion of water, the accelerated melting of the polar ice caps and glaciers, and resultant the accelerated melt and loss of the Greenland and West Antarctic ice sheets. All of these factors are induced by the on-going greenhouse effect and climate change. In fact, an estimated 80% of the additional heat caused by the greenhouse effect is absorbed by the world’s oceans, making it the largest heat sink.

The rapid rise of sea levels will have devastating effects on coastal ecosystems through inundation, erosion and damage from the powerful wave action from storms. As saline water moves inland, it will also contaminate freshwater sources and groundwater aquifers.

It will also severely impact the all communities who live in low-lying, coastal, and riverine regions. Some island nations such as Fiji and Maldives are already facing the threat of complete submersion.  You can explore this interactive map to see what will happen, should sea levels rise globally. Try zooming in on Bangkok, Hong Kong, or any of the island nations and assess the impact of a 2 meter, 5 meter, and 10 meter sea level rise.

In addition, watch this video to see what it would mean for Asia's coastlines, if all the Earth's polar ice melted

In 2015, an approximate 702 million people were living in extreme poverty with 793 million remaining undernourished globally. There is broad consensus that climate change is having adverse impacts upon agricultural productivity, resulting in global food insecurity and malnutrition.

The frequency and intensity of extreme events has affected harvests, infrastructure, and community assets. Rising sea levels will flood agriculturally productive deltas and riverine regions, while glacier melts will alter the availability of freshwater. Higher ambient global surface temperatures will impact drastically on production yields.

In addition, changing rainfall patterns will affect agriculture. Less rain is likely to fall in currently agriculturally productive regions, while other regions may experience more rain. This will cause fluctuations in food supply and access. The World Economic Forum has forecasted as much as a 20% drop in agricultural yields in many developing nations by 2050 as a result of climate change. 

You can explore this interactive map to view how varying levels of greenhouse gas emissions and adaptations to climate change can alter the distribution of food insecurity around the world.

Ocean acidification refers to the chemical reaction caused by the increasing uptake of carbon dioxide (a greenhouse gas) from the atmosphere by the oceans. These changes in ocean chemistry have a detrimental effect on marine ecosystems.

A decline in abundances of ocean organisms significantly diminishes the growth rate of important habitats like coral reefs, impacts the survival and developmental cycles of other species, and drastically alters the trophic levels/structure of the marine ecosystem. In turn, global commercial fisheries and a number of other ecosystem services the oceans provide to humans are also negatively affected.

You can read more on the impacts of ocean acidification upon marine biodiversity here

Source: NOAA PMEL Carbon Program (2008)