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What’s the big deal about a few degrees?

In a previous post, I espoused the importance of providing the climate change context when your company decides to embark on carbon emission reduction projects.  I described how discussions about calculating and reducing emissions can be “teachable moments.” These discussions can be conducted in a non-threatening way that results in an informed and intentional decision about the company’s position on climate change.  I also discussed the importance of using credible information as the foundation for this conversation with your sustainability committee and the decision makers who influence activity and external reporting.

For me, the most credible source for information on climate realities comes from the Intergovernmental Panel on Climate Change, otherwise known as the IPCC.  The IPCC is a scientific, intergovernmental entity established by the United Nations in 1998 “to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.”[1] In accordance with its mission, every few years the IPCC issues a series of reports. The first of five report series was issued in 1990, and the first document in the most current, Fifth Assessment report series (AR5) was released in September 2013.

Why is the information from the IPCC so credible? The disciplined process that is followed in the effort to compile the reports (see Figure 1) results in an extraordinary breadth and depth of expertly reviewed information.

Figure 1. Summary description of the IPCC writing and review process[2]

But, don’t take my word for it – decide for yourself. The following is summary of the research and scientific knowledge base behind the latest report:[3]

  • 209 lead authors and 50 review editors from 39 countries
  • Over 600 contributing authors from 32 countries
  • Over 2 million gigabytes of numerical data from climate model simulations
  • Over 9200 scientific publications cited
  • 54,677 comments, 1089 expert reviewers from 55 countries, 38 governments

For the AR5 series, three separate Working Groups will release documents.  Working Group I is focused on the Physical Science, Working Group II on Impacts, Adaptation, and Vulnerability, and Working Group III on Mitigation. So far, only the Working Group I findings have been formally issued,[4] and those findings have been summarized very well by Chester County Citizens for Climate Protection (4CP) in their newsletter supplement here. (Note: the summary would make a very good handout for your internal meetings.)  I have pulled out some key points from the 4CP summary and listed them below, but it is worth it to download and read the two page document yourself.  The IPCC also creates a Summary for Policymakers, which is available here, but it is still fairly long and likely too detailed for the average corporate audience.

IPCC Fifth Assessment Report (WGI) Key Points

  • Temperatures continue to rise: “Warming of the climate system is unequivocal.”
  • It is DEFINITELY hotter now: “In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years.”
  • There is NO pause in global warming: The word “pause” is not used. However, the “reduction in surface warming trend over the period 1998-2012” is attributed to 1) lower radiative forcing[5] caused by volcanic eruptions and being on the downside of the 11-year solar cycle, and 2) changes in internal heat distribution with the oceans (extensive la Niña periods).
  • Ice continues to melt: “Over the last two decades, the Greenland and Antarctica ice sheets have been losing mass…. It is very likely that the Arctic sea ice will continue to shrink….”
  • Oceans continue to warm: “Ocean warming dominates the increase in stored energy in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010.”
  • Therefore, sea level continues to rise: “The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.  …[G]lacier mass loss and ocean thermal expansion from warming together explain about 75% of the observed global mean sea level rise…. It is virtually certain that global mean sea level rise will continue beyond 2100.”
  • Ocean acidity continues to rise: “The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification.”
  • Human influence on the climate system is clear: “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”  The “extremely likely” wording translates to a 95-100% certainty in the IPCC likelihood assessment. This likelihood has increased in each of the IPCC’s Assessment Reports.
  • Cumulative anthropogenic CO2 emissions must be limited: “Cumulative total emission of CO2 and global mean surface temperature are approximately linearly related…. A large fraction of anthropogenic climate change resulting from CO2 emissions is IRREVERSIBLE (emphasis added) on a multi-century to millennial time scale….  Limiting the warming … with a probability of >66% to less than 2ºC … will require cumulative CO2 emissions from all anthropogenic sources” to be limited. After accounting for all non-CO2 effects, this limit is 800 GtC. “An amount of 531 GtC was already emitted by 2011.”  This is the first time that the climate science community has identified the upper limit of emissions.

At the end of the day, we need to be able to answer that ever important and critical question, “So what?” What is the big deal if the mean temperature rises a few degrees?  To most of us, a change of a few degrees doesn’t mean much.  Temperatures frequently fluctuate 15 or even 20 degrees in a single day.  This makes it difficult for people to comprehend the significance of what climate science is telling us.

One approach I have found to be effective for putting this in context for people is to present the following data point from NASA’s website: “Small changes in temperature correspond to enormous changes in the environment. For example, at the end of the last ice age, when the Northeast United States was covered by more than 3,000 feet of ice, average temperatures were only 5 to 9 degrees cooler than today.”[6]

Several other sources of information can also help to put the scientific conclusions into context. These include the World Bank report, Turn Down the Heat: Why a 4°C Warmer World Must be Avoided, and the PriceWaterhouseCoopers report Too Late for Two Degrees, which argues that businesses need to be prepared for unpredictability and challenges based on future projections pertaining to our changing climate.