Our Changing Climate: A current look at the science and mitigation of global climate change

By Lora Winslow, MELP, Environmental Advocate

OurChangingClimate_photo_1_WEBWith 2012 being the hottest year on record in the United States and recent increases in droughts, wildfires, coastal super storms, and other extreme weather events, climate change is on the minds of many people these days. However, the topic can often be overwhelming, confusing, and discouraging; leaving us feeling helpless and ineffectual against this multifaceted global problem. The goal of this article is to make the issue less daunting and more understandable by giving a basic overview of climate change science, discussing the impacts that are happening already and predicted to occur in the future, defining key terms, outlining what’s currently being done on a larger scale to both mitigate and adapt to climate change, and listing easy steps we all can take to reduce our carbon footprint.


If you’ve ever been in a greenhouse, you know the air is quite warm. The sun’s heat is able to enter the structure, but the majority of it gets trapped inside. On a much larger (and more complex) scale, this same principle forms the foundation of climate science. When the sun’s energy reaches the Earth’s surface, about 30% is reflected directly back into space and the rest is absorbed into the Earth’s system. During this absorption process, the planet releases some of the energy back into the atmosphere as heat. Certain gases in the atmosphere—called “greenhouse gases” (GHGs)—absorb this released heat, which slows or prevents the loss of the heat to space, and then re-emits the energy in all directions; warming the Earth’s surface and lower atmosphere. The U.S. Environmental Protection Agency (EPA) poses a great analogy: GHGs are like a blanket, because they make the planet warmer than it would be otherwise.


Types of Greenhouse Gases
(Source: U.S. EPA)

The three primary GHGs are carbon dioxide CO2, methane, and nitrous oxide. Carbon dioxide is the most prevalent GHG emitted into the atmosphere by a large margin (i.e. CO2 represented 84% of GHGs emitted in the U.S. between 1990 and 2011); this is why reducing CO2 is predominant in climate change conversations and efforts. However, the other GHGs are equally concerning for different reasons; i.e. one molecule of methane is 25 times stronger than CO2, and the impact of one pound of nitrous oxide is 300 times greater than one pound of CO2. Nitrous oxide has also been linked with a number of adverse effects on the respiratory system and is one of the air pollutants regulated by the EPA under the Clean Air Act.


Sources of Greenhouse Gases (Source: U.S. EPA)

The earth’s climate has changed many times throughout its history. According to the EPA, climate changes prior to the Industrial Revolution in the 1700s can be explained by natural causes; however the recent changes in climate cannot be explained by natural causes alone. The scientists from the IPCC* have determined with very high confidence that most of the observed increase in global average temperatures since the mid-1900s is due to an increase in GHG emissions from human activities. The majority of GHGs come from burning fossil fuels; although deforestation, industrial processes, and agricultural practices also contribute. The sources of GHG emissions in the US are electricity generation (33%); transportation (28%), industry (20%), heating for commercial and residential buildings (11%), and agriculture (8%). Even as one individual, there are things you can do in all five of those areas to help reduce emissions.

*Note: the bold, italicized terms are defined at the end of the article


It is almost impossible to predict precisely what will happen as global temperatures increase; not only are the types and severity of impacts dependent on how much the temperature actually increases (depending on emission levels, global temperatures are predicted to rise 1.1 – 6.4 ˚C by the end of this century), but scientists also don’t know exactly how various factors and impacts will affect and exacerbate others. Having said that, each time the IPCC releases a comprehensive report, the projected likelihood of impacts and the scientific confidence backing the findings both increase.

The effects of climate change are far reaching and diverse, and include the following impacts predicted by the world’s leading climate scientists: increase in frequency and severity of storms; sea level rise; increase in droughts and heat waves; increase in ocean temperatures and acidity; increased food production in some regions and decreased production in others; increase in coastal erosion and flooding; changes to ecosystems and species’ habitats; water scarcity in some regions; and an increase in public health issues, to name a few. Every one of these impacts is already occurring to some degree.

It is important to note the difference between climate and weather: weather consists of real phenomena that can typically be measured precisely (clouds, precipitation, heat, fog, humidity, etc.) and climate is the record of weather over time. Therefore, when scientists say the climate is changing or the globe is warming, they are not attributing that to one individual weather event or the fact that one year was warmer than the year prior; they are referring to changing weather trends over very long periods of time.

Many scientists predict that in order to avoid the most damaging effects of climate change, the atmospheric concentration of CO2 cannot exceed 500 parts per million (ppm). In the spring of 2013, the concentration of CO2 reached 400 ppm for the first time, gravely concerning experts. It is unclear what exactly could happen if atmospheric concentrations exceed 500 ppm, but some scientists fear we could experience global tipping points at that level (e.g., a complete melting of Greenland’s glaciers). GHGs are very persistent in the atmosphere, so their impacts are actually felt for 50-100 years after they’re emitted. So, even if all emissions completely halted today, we would be affected by current emission levels for the next century. This is why so much emphasis is placed on the need to not only stop increasing emissions, but to actually start reducing them.


OurChangingClimate_photo_2_WEBClimate change mitigation is the act of reducing GHG emissions. A large percentage of mitigation is happening through technology development—e.g., increasing fuel efficiency of vehicles, harnessing sources of renewable energy, replacing fossil fuels with biofuels, increasing the efficiency of buildings, carbon capture and sequestration technology, etc. Other mitigation efforts include reforestation projects (to create more natural carbon sinks), changes in agricultural and soil management practices, revised urban planning and transportation systems, and the creation of carbon markets.

Climate change adaptation is three-fold: (1) taking preventative measures to avoid the worst damages from climate changes (e.g., rezoning coastal development areas, safeguarding freshwater supplies, rebuilding and strengthening infrastructures, etc.); (2) adapting to the changes that are already occurring (e.g., growing new crops, replacing asphalt in cities with green space to reduce heat, public health education, etc.); and (3) disaster management and recovery (i.e. rebuilding after an extreme weather event). The primary goals of climate change adaptation are to increase resiliency and decrease vulnerability. While some argue that adapting to climate change represents a defeatist attitude, because GHGs persist in the atmosphere for a century and climate change is already happening, adaptation has to occur alongside mitigation efforts.


Although there is still a long way to go in addressing this global problem, progress is being made all the time and some exciting developments have happened in the last few years. Wind and photovoltaic electricity has been growing rapidly and exponentially, with other renewable energy sources like geothermal, tidal, and landfill gas being developed. An increase in electric, hybrid, and more fuel efficient cars is reducing GHG emissions from the transportation sector. Green building practices, non-fossil fuel heating sources, and increased building efficiency is reducing GHG emissions from the residential and commercial sector. More and more businesses are employing sustainability directors to help reduce the company’s carbon footprint, and a movement is happening across the US to get colleges to divest from fossil fuel corporations.

On an international level, the many nations that comprise the UNFCCC convene annually to negotiate their commitments for addressing climate change. On the federal level, President Obama unveiled a comprehensive climate change plan for the executive branch of the government in the summer of 2013. State and local governments across the country are also working to mitigate and adapt to climate change. The Regional Greenhouse Gas Initiative (RGGI) was established in 2009, creating a regional carbon cap-and-trade system for nine northeast states (including Maine). In October 2013, the governors from Oregon, Washington, and California, and British Columbia’s Premier signed the Pacific Coast Action Plan on Climate and Energy, committing to work together to address climate change. In 2006, California enacted a first-of-its-kind comprehensive climate change law to reduce emissions generated within its borders. To date, 1,060 mayors across the country have signed the U.S. Conference of Mayors’ Climate Protection Agreement; committing to reduce carbon emissions in their cities below 1990 levels. Additionally, numerous states, cities, and towns have adopted climate adaptation plans.

Climate change is a global problem affecting the world on the international, national, regional, state, and local level…and in order to prevent the most damaging impacts of climate change, the issue must be addressed on every level as well. So what can we do as individuals? Pursue and support large-scale efforts, while taking steps to reduce your personal impacts.


  • BicyclesChange your light bulbs to ENERGY STAR® rated bulbs and look for ENERGY STAR® rated appliances and electronics
  • Unplug electronics and turn off power strips when you’re not using them
  • Install an automatic timer on your thermostat
  • Replace your heating and/or cooling systems with efficient options that don’t utilize fossil fuels (air pumps, pellet boilers and stoves, biofuels, passive solar, wood stoves, etc.)
  • Make sure your heating/cooling systems are properly maintained
  • Seal and insulate your home
  • Purchase green electricity or generate your own power with solar panels
  • Compost your food scraps and reduce, reuse, recycle to minimize what ends up in landfills
  • Choose vehicles with high fuel efficiency
  • Don’t idle your car unnecessarily (in drive-throughs, at train tracks, etc.)
  • Drive the speed limit, remove excess weight from your car, use cruise control whenever appropriate, and regularly check your tire pressure
  • Keep your car maintained and tuned up
  • Commute a different way—walk, bike, use public transportation, carpool, etc.
  • Grow your own food and/or support local farmers, fishermen, and producers
  • Calculate your household’s carbon footprint to learn areas where you can make further reductions


  • Biofuels (ethanol, biodiesel): Fuels made from biomass materials (living organisms) – e.g., ethanol is an alcohol fuel made from the sugars found in grains and biodiesel is fuel made from vegetable oils, fats, or greases
  • Cap-and-Trade: A market system for reducing GHG emissions. A cap is set on total emissions and participating parties (businesses, municipalities, etc.) are given allowances for their individual annual emissions. Parties can only generate the amount of emissions they have allowances for, but can buy, sell, or trade these credits within the market
  • Carbon Capture & Sequestration: Technology that captures CO2 from power plants and industrial processes and stores it in underground rock formations
  • Carbon Market: Using an economic market system to reduce GHG emissions; the two types of carbon markets are cap-and-trade systems (see above) and a carbon tax (charging emitters per ton for the GHGs they produce annually)
  • Carbon Sink: A term used to describe how trees and vegetation naturally absorb CO2 from the atmosphere and store it
  • IPCC (Intergovernmental Panel on Climate Change): The leading international body for climate change assessment
  • Photovoltaic: Generating an electric current with the exposure of light (e.g., solar power)
  • Tipping Points: A critical threshold that, when crossed, fundamentally and irreversibly changes a system
  • UNFCCC (United Nations Framework Convention on Climate Change): The international body addressing climate change through treaty law

Lora has a Masters of Environmental Law & Policy from Vermont Law School with a concentration in climate change and more than a decade of professional experience in the environmental field.

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2 Responses to “Our Changing Climate: A current look at the science and mitigation of global climate change”

  1. stephen cole January 23, 2014 at 4:35 pm #

    This is the best, most comprehensive article on climate change I’ve ever read. It deserves a wide distribution and readership. Kudos to Lora.

  2. Doug Malcolm February 4, 2014 at 12:05 pm #

    I agree with Stephen. Highly informative. Clearly connects the dots. Sober, yet hopeful, with concrete suggestions for how to make positive changes while shrinking one’s footprint. Thanks, Lora! Good job!! And, yes, please, get this out there as widely as possible.

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