Climate scientists such as Andrew Dessler have been studying modern climate change for years on end. Global warming has been the talk of the century with many scientists claiming its existence while others controversially denounce it. In his book “Introduction to Climate Change”, Dessler covers the underlying science of global warming and its associated economic and policy issues. From a professional stand point, Dessler offers insight into the physics and chemistry behind climate change. He also explores the impact climate change has on the economy of a nation. The book contains fourteen chapters. The first seven chapters of the book explain the science behind global warming while the other seven chapters explore the economic and policy issues.
Dessler explores why the climate has been changing over the years in Chapter 7. Climate change occurs due to external or natural variations, human activities or sometimes a combination of both. Dessler’s strategy involved examining if the mechanisms that caused climate change in the past was responsible for the recent warming. The earth’s climate can change due to tectonic motions which can alter the arrangement of continents on the earth’s surface. High latitude areas such as Greenland and Antarctica are covered by ice sheets which reflect sunlight causing the planetary albedo. When continents move, they can also change the rainfall patterns while also exposing new rock formations. However, it is important to note that it would take millions of years for tectonic motion to cause significant changes in the climate.
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The sun is also a factor that controls climate. Scientists have tried to explain how the solar output affects climate change. The temperature of the sun has been measured and the data reveals that the sun has become 30% brighter over time (Dessler, 2016). The solar output that has been measured over the past few decades does not show increase in the solar constant. This concludes that the sun is not responsible for the recent warming. As the earth orbits, it causes changes in the climate. The average amount of solar energy reaching the earth’s surface reduces with increase in the earth- sun distance. These orbital variations are so slow hence any significant change in incoming sunlight would be observed after many years. The El Nino and La Nina events causes temperature changes after every few years where warm and cool temperatures are experienced respectively. These events cause temporary temperature changes as opposed to long term climate change. Greenhouse gases on the other hand have been attributed to causing warming of the earth. High levels of carbon dioxide in the earth’s atmosphere has been recorded for many years and this has been linked to the temperature changes. Human activities that lead to the emission of greenhouse gases have greatly attributed to the global temperature changes. Evidence suggests that greenhouse gases have been the cause of the latest warming (Dessler, 2016).
The future of our climate greatly depends on the amount of greenhouse gases in the atmosphere. In predicting climate change, projections of greenhouse gas emissions known as emission scenarios are used. An analysis of the factors that control emissions pave the way for prediction. The GDP of a society can be used to measure the amount of greenhouse gases released by that society. Emissions in a society are therefore directly linked to the GDP. The population of a country affects the GDP hence the population also affects emission rates. If everything else remained the same and the population doubled, the emission rates would also double. Due to high fertility rates, population has been rapidly increasing over time. An 80% increase in population over the last few decades has seen an increase of 200,000 people a day. Affluence, measured as the GDP per person has also increased by 80% in the 21 st century. Technology on the other hand has seen rapid changes especially in terms of energy consumption. New technology now consumes less energy compared to technology that existed in the past.
Predictions of the future climate is uncertain however, the IPCC has set alternative scenarios of how the world might evolve. Predictions on population changes put it at about 9 and 10 billion people by mid-21 st century. Factors such as high fertility rates, better living and working conditions and improved healthcare will attribute to the rise in population. Affluence is influenced by factors such as law, education and technology. Experts predict that the level of affluence in developing countries will be at 2-3% per year and 1-2% per years for developed nations. Advancements in technology will help reduce energy intensity by 1% per year. Emission scenarios from the IPCC shows possible future predictions of the climate. The scenarios show that by the end of the 21 st century, the earth will be warmer by 1.8–3.6°C with temperatures increasing by 0.4°C. The scenarios can predict beyond the year 2100.
The impact of the warming of the earth’s surface has been felt on many places on earth. In 2010 for example, Russia experienced heat waves caused by the global rise in the earth’s temperature. The rate of warming of the earth is a major concern and hence people are required to adapt faster to their changing environments. This has also caused rise in sea levels. The global average temperature increase is not uniformly distributed. This is evidenced in the high latitude regions warming faster than areas in the tropics. The continents also experience more warming than the oceans. Continual release of greenhouse gases into the earth’s atmosphere causes heating of the earth’s surface making the surface warmer. Increased surface temperatures lead to increased evaporation of water from the oceans and seas. This in turn leads to increased levels of precipitation for every degree Celsius of warming. Although total rainfall is expected to increase, it will not be evenly distributed. High latitude areas will experience an increase in precipitation while a decrease will be experienced in subtropical regions. During warmer summers, the intensity of drought is observed since a lot of water from the soil is lost through evaporation. Wet and dry extremes are most likely to be observed in the future where soil erosion, flooding and landslides may occur.
Sea levels rise due to the climate changes experienced. Warm temperatures melt the grounded ice which run into the oceans increasing the total amount and therefore causing a rise in the sea levels. Sea levels also rise due to the expansion of water which is caused by the warm temperatures experienced. The oceans absorb carbon dioxide and converts it to carbonic acid in a process called ocean acidification. This in turn affects the water by making it more acidic. Extreme increase in temperature is also harmful to the health of a human being. This temperature increase is detrimental to agriculture since yields decline at temperatures above 30°C. The warming affects some eco systems evident in the decline of the lizard species. Some species will eventually adapt to the changing temperatures while others will be wiped out of existence completely. The rising temperatures have also caused the loss in sea ice in the Artic regions. This has greatly affected ecosystems and wildlife present in these regions. The changes in precipitation positively impacts some regions by providing increase river run-off and fresh water availability and negatively impacts other regions by reducing water resources. Rising sea levels will discourage settlement areas that are close to the sea shore due to flooding. The acidification of oceans will cause certain animals to die when the levels become too acidic.
In conclusion, we note that since warming is not evenly distributed, its effects and impact will be different in certain regions. Dessler’s insight into modern climate change reveals that greenhouse gases are the cause of the recent warming experience on earth. The impact of this warming is being felt in the oceans, agriculture, health and other sectors. It is imperative to note that the evidence of climate change is real and can be observed with ease hence there is a need to ensure that greenhouse gases levels are reduced in order to reduce the effects of climate change.
References
Alley, R. (2007). Climate change 2007, the physical science basis: Summary for policymakers: Contribution of Working Group I to the Intergovernmental Panel on Climate Change. Geneva, Switzerland: IPCC Secretariat.
Dessler, A. E. (2016). Introduction to modern climate change . Cambridge: Cambridge University Press.
Introduction to Modern Climate Change. (n.d.). Retrieved March 22, 2018, from https://www.aps.org/units/fps/newsletters/201304/climate.cfm
Lynas, M. (2008). Six degrees - our future on a hotter planet. Harpercollins.
