My good friend Larry Chamblin, active member of 350-Pensacola, has summarized the Third National Climate Assessment which outlines impacts on our region now and in the future. See his notes below. Especially review the “What We Can Do” notes which give us solid direction for community planning and action.
General statements
The NAC affirms that climate change is already affecting every region of the US–including Northwest Florida.
Global warming over the past 50 years is primarily cause by human activities (burning fossil fuels and deforestation). Global average temperature has increased by more than 1.5 degrees since record keeping began in late 1800s, and most of this increase has occurred since 1970. US temperature has increased by 1.3 degrees F to 1.9 degrees F. (NW FL, Alabama and some other areas of the SE US have avoided this warming and have even seen a slight decrease in average temperatures; but projections show the region will not avoid future warming.)
The rise in global average temperature parallels the rise in the concentration of carbon dioxide.
The decade of 2000-2010 was the nation’s warmest on record. Human-induced warming adds to natural climate cycles. (A baseball slugger who take steroids becomes a super-slugger.)
Over the past five decades, natural factors alone (solar forcing and volcanoes) would have resulted in a slight cooling.
Scientists today are more confident of the warming trend of the past and projected warming because they have a greater understanding of the dynamics of climate change and of the US temperature records. (Of course uncertainties remain about some specifics of future impacts.)
Computer models have generally been accurate in projecting melting ice, rising temperatures, rising seas, and extreme weather events. In some cases the models underestimated the changes, including the melting of sea ice. A record low of Arctic sea ice was set in 2012.
Indicators of global warming observed over many decades include the following: shrinking of sea ice; higher sea surface temperature; higher temperature over oceans and land; increased water vapor; higher sea level; reduced size of glaciers, ice sheets, and snow cover. Even if we stopped all emissions today, greenhouse gas emissions already in the atmosphere would continue to drive warming over the next few decades. But choices made today will determine how much future warming occurs.
Projected Impacts
Changing climate key impacts in SE US:
1. Sea level rise poses widespread and continuing threats to both natural and built environments and to the regional economy.
2. Increasing temperatures and the associated increase in frequency, intensity, and duration of extreme heat events will affect public health, natural and built environments, energy, agriculture, and forestry.
3. Decreased water availability, exacerbated by population growth and land-use change, will continue to increase competition for water and affect the region’s economy and unique ecosystems.
Sea Level Rise “Global sea level rise has been a persistent trend for decades. It is expected to continue beyond the end of this century, which will cause significant impacts in the United States. Scientists have very high confidence (greater than 90% chance) that global mean sea level will rise at least 8 inches (0.2 meter) and no more than 6.6 feet (2.0 meters) by 2100.”
NW FL is less vulnerable to the impacts of sea level rise than some other areas, including Miami, and New Orleans. But the impact of Ivan was worse because of higher seas and this region is vulnerable to the combined effects of higher seas and stronger storms.
Projected temperature change In Escambia/Santa Rosa and NW FL, warming to the end of the century is projected to range from a low of 3 degrees F to a high of 6 degrees F–depending on whether we make substantial reductions in emissions soon or continue with business as usual. The hottest days will be at least 10 degrees hotter.
“Extreme heat will affect health, energy, agriculture, and more. Decreased water availability will have economic and environmental impacts.”
Precipitation changes
Observed precipitation change to date reported by the NCA show that NW FL has seen a 0-5% increase (data do not include April 2014). Rapid and substantial reductions in emissions could keep total amount of annual rain in NW FL about where it has been in recent years. However, failure to reduce emissions–business as usual–will likely bring a 10% increase in total amount of annual rain in NW FL and a 20% increase in much of the NE US. NCA projections show that NW FL will experience an increase in heavy downpours of the kind we have recently experienced. Heavy rains have increased by 27% during the last century through 2012. If we reduce emissions substantially in the immediate future, heavy precipitation events (deluges, heavy downpours) will occur nearly twice as often as in the past; if we fail to make such reductions, we can expect to see three times more downpours in future decades.
Hurricanes
The NCA projects a slight decrease in the annual number of Atlantic hurricanes but an increase in the number of the strongest hurricanes (Category 4 and 5). At the center of these hurricanes, models project a 20% increase in rainfall.
What we can do
The National Climate Assessment reminds us that “Americans face choices.” Future impacts of climate change “will still largely be determined by choices society makes about emissions.”
“Global climate is projected to continue to change over this century and beyond, but there is still time to act to limit the amount of change and the extent of damaging impacts.”
“It is important that these findings and response options be shared broadly to inform citizens and communities across our nation. Climate change presents a major challenge for society. This report advances our understanding of that challenge and the need for the American people to prepare for and respond to its far-reaching implications.”
From a National Oceanic and Atmospheric Administration report cited by the NCA says that the higher sea levels projected “increase the frequency, magnitude, and duration of coastal flooding associated with a given storm.”
Local planners need to take into account the combined effects of higher seas and stronger storms “in developing hazard profiles for emergency planning and vulnerability, impact, and adaptation assessments.”
“Mitigation [reducing emissions of heat-trapping gases] and adaptation actions are linked in multiple ways, including that effective mitigation reduces the need for adaptation in the future. Both are essential parts of a comprehensive climate change response strategy.”
Mitigation actions are being taken today but they are insufficient to meet the challenge of increasingly negative impacts. “Both ‘bottom up’ community planning and ‘top down’ national strategies may help regions deal with impacts such as increases in electrical brownouts, heat stress, floods, and wildfires.”
“Using scientific information to prepare for climate changes in advance can provide economic opportunities, and proactively managing the risks can reduce impacts and costs over time.”
“Cities providing transportation options including bike lanes, buildings designed with energy saving features such as green roofs, and houses elevated to allow storm surges to pass underneath are among the many response options being pursued around the country
Susan Feathers 