Effects of Global Warming: Climate Change – The World’s Health

Roughly 40 years ago, a small group of scientists and policy makers began to realize that humanity was on a dramatic collision course, as the rapidly growing world economy and population threatened to collide with the planet’s finite resources and fragile ecosystems. The danger was first highlighted globally at the 1972 UN Conference on the Human Environment in Stockholm. A famous and influential book published that same year, Limits to Growth, warned that business as usual could lead to a collapse in the twenty‐first century.

The globe is heating up. Both land and oceans are warmer now than record‐keeping began in 1880, and temperatures are still ticking upward. This temperature rise, in a nutshell, is global warming. Altogether, climate change is therefore one very tough issue, and time is running out! The emissions of the main GHGs that lead to human‐induced climate change are increasing each year, and the threats to the planet are growing as well. We are losing time even though the stakes for the planet are incredibly high.

Here are the bare numbers, according to the NOAA. Average surface temperatures rose a total of 0.95 ^°C (1.71 °F) between 1880 and 2016. The pace of change has been an additional 0.07 °C (0.13 °F) per decade, with the land surface warming faster than the ocean surface – 0.10 °C (0.18 °F) vs. 0.06 °C (0.11 °F) per decade, respectively. The average global temperature anomaly for the past 140 years is plotted in Figure 3.2. As can be seen in Figure 3.2, the bulk of the warming has occurred in two periods – from 1910 to 1940 and from 1980 to the present.

The Paris Agreement, ratified by 174 nations of 197 nations as of the summer 2017, aims to halt that warming at 1.5 °C (2.7 °F) above Earth’s average temperature during preindustrial times – a goal most scientists and policy makers agree will be a challenge to meet. Here’s how humanity has managed to heat up the planet.

The Greenhouse Effect

The basic physics and human‐induced climate change were already worked out by scientists in the nineteenth century. One great scientific genius, Svante Arrhenius, a Swedish Noble laureate in chemistry, calculated accurately by hand, without a computer, the effects of doubling the atmospheric concentration of carbon dioxide (CO₂) (Arrhenius 1896). And he did so back in 1896! He correctly calculated that a doubling of the CO₂ in the atmosphere would cause a rise in the mean temperature of the planet at around 5 °C, an estimate that is within the likely range today based on advanced computer models and vastly more extensive data than Arrhenius had at his disposal.

The main driver of today’s warming is the combustion of fossil fuels. The main contributor to global warming and climate change over the past century has been carbon dioxide; however, three other gases are now significant – methane, nitrous oxide, and CFCs. These hydrocarbons heat up the planet via the greenhouse effect, which is caused by the interaction between Earth’s atmosphere and incoming radiation from the sun. According to Weiner (1990) and Pilson (2006), Arrehenius summed all up as follows:

We are evaporating our coal mines into the air…..[which must eventually cause] a change in the transparency of the atmosphere.

Greenhouse Gases

Since the beginning of the industrial revolution, humans have been rapidly changing the balance of gases in the atmosphere. Burning fossil fuels like coal and oil releases water vapor, carbon dioxide (CO₂), methane (CH₄), ozone (O₃), and nitrous oxide (N₂O) – the primary GHGs. Carbon dioxide is the most common GHG. Between about 800 000 years ago and the beginning of the Industrial Revolution, its presence in the atmosphere amounted to about 280 ppm. Today, it’s about 405 ppm (Figure 5.19). (This number means there are 405 molecules of carbon dioxide in the air per every million air molecules.)

EXAMPLE 5.24 CALCULATING GHG MASS‐BASED AND CO₂E (EQUIVALENT)‐BASED EMISSIONS

For any source, since GHG emissions may be a mixture of up to six compounds, the amount of GHG emissions calculated for the PSD permit applicability analysis is a sum of the compounds emitted at the emissions unit. The following example illustrates the method to calculate GHG emissions on both a mass basis and CO₂e basis.

A proposed emissions unit emits five of the six GHG compounds in the following amounts:

• 50 000 TPY of CO₂
• 60 TPY of methane
• 1 TPY of nitrous oxide
• 5 TPY of HFC‐32 (a hydrofluorocarbon)
• 3 TPY of PFC‐14 (a perfluorocarbon)

The GWP for each of the GHGs used in this example are as follows:

GHG	GWPa
Carbon dioxide	1
Nitrous oxide	310
Methane	21
HFC‐32	650
PFC‐14	6500

^asee 40 CFR Part 98, Subpart A, Table A.1.

The GHGs mass‐based emissions of the unit are calculated as follows:

The CO₂e‐based emissions of the unit are calculated as follows:

In 2015, CO₂ accounted for about 82% of all US GHG emissions, according to an EPA inventory. “We know through high‐accuracy instrumental measurements that there is an unprecedented increase in CO₂ in the atmosphere.” We know that CO₂ absorbs infrared radiation [heat] and because of that the global mean temperature is increasing. CO₂ makes its way into the atmosphere through a variety of routes. Burning fossil fuels releases CO₂ and is by far the primary way that US emissions warm the globe. According to the USEPA’s 2015 report, US fossil‐fuel combustion, including electricity generation, releases just over 5.5 billion T (5 billion MT) of CO₂ into the atmosphere annually. Other processes – such as nonenergy use of fuels, iron and steel production, cement production, and waste incineration – boost the total annual CO₂ release in the United States to almost 6 billion T (5.5 billion MT).

EXAMPLE 5.25 CO₂ EMISSION FROM CARS

Assume an average car in the United States gets 20 miles/gal of gasoline, is driven 12 000 miles/year, and weighs 3 500 lb. Further assume that gasoline weighs 5.9 lb/gal and contains 85% carbon by weight. Is there any truth to the statement that each car emits its weight in carbon dioxide each year? Next, given that there are about 800 million vehicles worldwide, estimate the annual global carbon emissions from motor vehicles. Give your answer in Teragrams (1 Tg = 1 trillion grams = 1 MT) per year.

SOLUTION

The carbon contained in the gasoline burned annually is

The carbon dioxide emitted is

So the average US car emits much more than its own weight in carbon dioxide each year!

To estimate worldwide emissions from vehicles, we must make a number of gross assumptions as to the average vehicle in the world (including cars, trucks, buses, moto cycles, and so on). Let us assume that the average vehicle in the world travels 24 000 km/year, gets 9 km/l, and burns fuel with a density of 0.75 kg/l and with a carbon content of 87%. With these assumptions, annual carbon emissions

Deforestation is also a large contributor to excessive CO₂ in the atmosphere. In fact, deforestation is the second largest anthropogenic (human‐made) source of carbon dioxide. When trees are killed, they release the carbon they have stored during photosynthesis. According to the 2010 Global Forest Resources Assessment, deforestation releases nearly a billion tons of carbon into the atmosphere per year.

Methane is the second most common GHG, but it is much more efficient at trapping heat. In 2012, the gas accounted for about 9% of all US GHG emissions, according to the EPA. The EPA reports that methane has 20 times more impact than carbon dioxide on climate change over a 100‐year period.