Human-induced global warming and climate change isn't opinion. It's a scientific reality. And the science tells us that human activity has made, and continues to make, enormous impacts to our planet that affect our well-being and even our survival as a species. Many of the impacts are being felt along our coasts, both along the shore and in the water.
The world's leading science journals report that glaciers are melting ten times faster than previously thought and that atmospheric "greenhouse gases" like carbon dioxide (CO2) have reached levels not seen for millions of years. They also report of extreme weather events, long-term droughts, and rising sea levels.
As mentioned above and detailed further below, the scientific consensus is overwhelming – greenhouse gases emitted by human activity are causing average global temperatures to rise. This, in turn, is causing or contributing to:
Each of these has implications for surfers and others who enjoy coastal areas. While we may cynically hope that increased storm activity will result in more and better waves for us to surf, the reality is that the effects on our surfing experience are unpredictable, and the overall harm to human society will likely far outweigh any positives.
Sea level rise will have the following effects:
Disruption of major ocean currents are predicted, which may be ultimately responsible for changes to storm patterns and ecosystems, such as:
More frequent and more severe storm events will have positive and negative consequences:
Water temperature and acidity changes will have effects including:
Here are more documented facts about why all this is happening:
The atmosphere has a natural supply of "greenhouse gases." They capture heat and keep the surface of the Earth warm enough for us to live on. Without the greenhouse effect, the planet would be an uninhabitable, frozen wasteland.
Before the Industrial Revolution, the amount of carbon dioxide (CO2) and other greenhouse gases released into the atmosphere was in a rough balance with what could be stored on Earth. Through photosynthesis, for example, plants take in carbon dioxide while the process of respiration or metabolism releases CO2 back into the atmosphere.
The Industrial Revolution in the 1700s kick-started the process of factories and people emitting large amounts of greenhouse gases. Today, the fossil fuels we burn to run our cars, trucks, airplanes, factories and power plants add to the natural supply of greenhouse gases. The gases--which can stay in the atmosphere for at least fifty years--are building up beyond the Earth's capacity to remove the gases and, in effect, creating an extra-thick heat blanket around the Earth.
The result is that the globe has heated up by about one degree Fahrenheit over the past century--and it has heated up more intensely over the past two decades.
If one degree doesn't sound like a lot, consider this: the difference in global average temperatures between modern times and the last ice age--when much of Canada and the northern U.S. were covered with thick ice sheets--was only about nine degrees Fahrenheit. So in fact one degree is very significant--especially since the unnatural warming will continue for generations after we stop putting "extra" greenhouse gases in the atmosphere--assuming we actually stop.
Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases.
Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned.
Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock.
Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of solid waste and fossil fuels.
Very powerful greenhouse gases that are not naturally occurring include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes.
Each greenhouse gas differs in its ability to absorb heat in the atmosphere. HFCs and PFCs are the most heat-absorbent. Methane traps over 21 times more heat per molecule than carbon dioxide, and nitrous oxide absorbs 270 times more heat per molecule than carbon dioxide. Often, estimates of greenhouse gas emissions are presented in units of millions of metric tons of carbon equivalents (MMTCE), which weights each gas by its GWP value, or Global Warming Potential. Water Vapor is perhaps the most important greenhouse gas, in terms of absorbing heat. But many discussions omit mention of this because it does not actively worsen the problem, whereas other gases do. The reason water vapor does not worsen global warming is because it is cycled out of the atmosphere very quickly through precipitation – on average, a water droplet only stays in the atmosphere about 10 days, as opposed to many decades for some other gases. Increased water vapor in the atmosphere is the result of global warming, not a cause (not a "forcing"). Contrary to popular belief, scientists do account for the presence of water vapor when modeling global warming.
Already, people have increased the amount of CO2 in the atmosphere to 31 percent above pre-industrial levels. In the same period, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. There is more CO2 in the atmosphere now than at any time in the last 650,000 years. Studies of the Earth's climate history show that even small changes in CO2 levels generally have come with significant shifts in the global average temperature. Look at the graphs below and note the dramatic temperature increases and the rapid rise in CO2 levels in the last 100 years. The graph showing CO2 concentrations at the Mauna Loa Observatory in Hawaii is the famous Keeling Curve researched and maintained by scientists at the Scripps Institution of Oceanography.
Research published in March 2013 in the journal Science confirms these temperature trends (see graph above right). The study used fossils of tiny marine organisms to reconstruct global temperatures back to the end of the last ice age. The data indicate the globe was cooling for several thousands of years until an unprecedented reversal in the 20th century. The decade of 1900 to 1910 was one of the coolest in the past 11,300 years — cooler than 95 percent of the other years, the marine fossil data suggest. Yet 100 years later, the decade of 2000 to 2010 was one of the warmest, according to study lead author Shaun Marcott of Oregon State University. "Global temperature, therefore, has risen from near the coldest to the warmest levels of the Holocene within the past century,” the researchers wrote.
Scientists expect that by 2100, the global average temperature will increase another 2.5 degrees to 10.4 degrees Fahrenheit, more than they predicted just seven years ago. A couple degrees may not sound like much, but it took only a nine-degree shift to end the last Ice Age 14,000 years ago.
Even if the temperature change is at the small end of the predictions, the changes to the climate are expected to be serious: more intense storms, more pronounced droughts, and coastal areas more severely eroded by rising seas. At the high end of the predictions, the world could face abrupt, catastrophic and irreversible consequences.
In 1995, the world's climate experts in the Intergovernmental Panel on Climate Change (IPCC) concluded for the first time in a cautious consensus, "The balance of evidence suggests that there is a discernible human influence on the global climate."
In its 2001 assessment, the IPCC strengthened that conclusion considerably, saying, "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities." The IPCC continues to collect and analyze data on global climate change. Climate Change 2013: The Physical Science Basis was issued in September 2013.
Scientists have found significant evidence that leads to the above conclusion:
Most simulation models that take into account greenhouse gas emissions and sulfate aerosols (which have a cooling effect) are consistent with observations over the last 50 years.
Scientists are no longer debating the basic facts of climate change. In December 2004, Science magazine published an analysis of 928 peer-reviewed science papers on climate change from science journals between 1993 and 2003. The analysis found that not a single scientific article disputed the evidence that the climate is warming because of human activities.
Unfortunately, a similar analysis of media reports had very different findings: about half still framed the issue as a science debate.
The Science study showed the consensus among respected individual scientists. In a joint statement with 10 other National Academies of Science, the U.S. National Academy of Sciences said:
"The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action. It is vital that all nations identify cost-effective steps that they can take now, to contribute to substantial and long-term reduction in net global greenhouse gas emissions."--Joint Statement of Science Academies: Global Response to Climate Change, 2005
The American Geophysical Union, a respected organization comprising 50,000 Earth and space scientists in 137 countries, updated its position on climate change in 2007. Their position statement includes this quote: "With climate change, as with ozone depletion, the human footprint on Earth is apparent. The cause of disruptive climate change, unlike ozone depletion, is tied to energy use and runs through modern society. Solutions will necessarily involve all aspects of society."
What has changed in the last few hundred years is the additional release of carbon dioxide by human activities. Fossil fuels burned to run cars and trucks, heat homes and businesses, and power factories are responsible for about 98% of U.S. carbon dioxide emissions, 24% of methane emissions, and 18% of nitrous oxide emissions. Increased agriculture, deforestation, landfills, industrial production, and mining also contribute a significant share of emissions. The United States, with only four percent of the world's population, is responsible for 22% of the world's greenhouse gas emissions.
Estimating future emissions is difficult, because it depends on demographic, economic, technological, policy, and institutional developments. Several emissions scenarios have been developed based on differing projections of these underlying factors. For example, by 2100, in the absence of emissions control policies, carbon dioxide concentrations are projected to be 30% to 150% higher than today's levels.
Some people argue that these difficulties make the computer models, which scientists use to predict climate, inherently untrustworthy. For example, they note the wide range above (predicting a "30% to 150%" increase in carbon dioxide concentrations) appears to indicate great uncertainty, as well as the fact that weathermen can't really guarantee a certain temperature or wind speed next week, let alone a hundred years from now.
But exact numerical predictions are not the purpose, nor the value of climate models. For most experiments, scientists compare two or more different models and look at the difference in results. For example, they run a model to estimate future average temperatures including natural causes such as sun variation and volcanoes – and then run an identical model including natural causes plus human emissions. They may run dozens or hundreds of computer models in order to account for future variables, such as for example, whether forest area increases or decreases and thus absorbs more or less carbon dioxide. From comparing the two or more results, scientists can confidently make statements such as "By 2100, the global average temperature will increase another 2.5 degrees" and "most of the warming observed over the last 50 years is attributable to human activities."
Although there is a substantial amount of uncertainty associated with the model's point-by-point numerical results – such as what the model says the noontime temperature in Poughkeepsie will be in February of 2100 – that's not the purpose of the model. The purpose is to compare two (or more) scenarios against each other. The predictions that temperature will increase, and the conclusion that mankind's pollution is responsible, are rock-solid, so long as the models account for our best understanding of natural processes, and are in good agreement with measured data. Today's models do so and are in good agreement with measured data.
The video below, provided by the Space Coast Climate Change Initiative, provides a thorough overview of climate change science and the need to act.
Global mean surface temperatures have increased 0.5 to 1.0°F since the late 19th century. The 20th century's 10 warmest years all occurred in the last 15 years of the century. Of these, 1998 was the warmest year on record. The snow cover in the Northern Hemisphere and floating ice in the Arctic Ocean have decreased. Globally, sea level has risen 4 to 8 inches over the past century. Worldwide precipitation over land has increased by about one percent. The frequency of extreme rainfall events has increased throughout much of the United States.
As can be seen on the graph, the trend is clearly and sharply upwards, even despite some brief episodes of cooling such as 1940 to 1970.
Increasing concentrations of greenhouse gases are likely to accelerate the rate of climate change. Scientists expect that the average global surface temperature could rise 1 to 4.5°F (0.6 to 2.5°C) in the next fifty years, and 2.2 to 10°F (1.4 to 5.8°C) in the next century, with significant regional variation. Evaporation will increase as the climate warms, which will increase average global precipitation. Intense rainstorms are likely to become more frequent. Sea level may rise as much as two feet along most of the U.S. coast.
A few people argue that rising global temperatures will be a boost to agriculture and make cold areas more hospitable. But studies indicate that the negatives outweigh the positives. The spread of diseases, pests and parasites appears to move faster with rising temperatures than the net benefit to civilized agriculture. Temperate areas, where large populations currently live, will be and in fact are being "squeezed" between expanding deserts, pointing towards decreased overall habitability of the planet for humans. Both of these problems include effects from many other sources than global warming, but the overall prognosis is not good news.
More and more attention is being aimed at the possible link between El Niño events – the periodic warming of the equatorial Pacific Ocean – and global warming. Scientists are concerned that the accumulation of greenhouse gases could inject enough heat into Pacific waters such that El Niño events, which are often linked to the formation of devastating storms, may become more frequent and intense.
Higher sea levels are one of the most certain consequences of global warming. The massive ice sheets in the Arctic are melting at alarming rates. Glaciers store water on land. When these huge ice masses melt into the oceans, it adds volume and water levels rise. Additionally, water expands as it gets warmer. So as the temperature rises, the same amount of water takes up more space. This raises sea levels higher.
Most of the world's population lives on or near the coasts. By 2025, 75% of the residents of the United States will live within 80 miles of the coast (Pew Oceans Commission). Rising ocean levels could cause massive devastation and economic catastrophe to coastal population centers worldwide.
NOAA's Sea Levels Online website illustrates regional trends in sea level, with arrows representing the direction and magnitude of change.
Sea level is rising more rapidly along the U.S. coast than worldwide, due to specific local conditions such as the tectonic subsidence of land. Studies by EPA and others have estimated that along the Gulf and Atlantic coasts, a one foot (30 cm) rise in sea level is likely by 2050. In the next century, a two foot rise is most likely, but a four foot rise is possible; and sea level will probably continue to rise for several centuries, even if global temperatures were to stop rising in a few decades.
A good indicator that global warming is an existing threat, not a theory, is that major insurance companies, who stand to pay more money from disaster claims versus lose money if their predictions are exaggerated, have indeed begun to bet on rising seas and damaging weather events. Federal, state, and local governments are also taking measures to prepare for the consequences of rising sea level. More specific examples are found in the discussion below.
Rising sea level inundates wetlands and other low-lying lands, erodes beaches, intensifies flooding, and increases the salinity of rivers, bays, and groundwater tables. Some of these effects may be further compounded by other effects of changing climate. Measures that people take to protect private property from rising sea level may have adverse effects on the environment and on public uses of beaches and waterways.
Coastal marshes and swamps are particularly vulnerable to rising sea level because they are mostly within a few feet of sea level. As the sea rises, the outer boundary of these wetlands will erode, and new wetlands will form inland as previously dry areas are flooded by the higher water levels. The amount of newly created wetlands, however, will typically be much smaller than the area of wetlands that are lost. The amount of dry land within a few feet above the wetlands is much less than the area of wetlands that would be lost if sea level rises a few feet. Moreover, developed areas will often be protected with bulkheads, dikes, and other structures that keep new wetlands from forming inland.
Nationwide, a two foot rise in sea level could eliminate 17 to 43 percent of US wetlands, even if no additional bulkheads or dikes are erected, with more than half of the loss taking place in Louisiana alone.
The dry land within a few feet above high tide includes forests, farms, low parts of some port cities, communities that sank after they were built and are now protected with levees, parts of deltas, and the bay sides of barrier islands. The low forests and farms are mostly in the Mid-Atlantic and Southeast. Major port cities with low areas include Boston, New York, Charleston, Miami, and New Orleans. The average elevation of New Orleans is about 2 meters below sea level, and parts of Texas City, Texas and San Jose and Long Beach, California are about one meter below sea level.
Nationwide, about 5000 square miles of dry land are within two feet of high tide elevation, 4000 of which are currently undeveloped. All of this land could be inundated by rising sea level, unless additional dikes and bulkheads are constructed. Including both the wetlands and dry land that would be lost to the sea, a two foot rise in sea level would eliminate approximately 10,000 square miles of land, an area equal to the combined size of Massachusetts and Delaware.
Some of the most economically important vulnerable areas are the recreational resorts on the "coastal barriers" of the Atlantic and Gulf coasts. In many cases, the ocean-front block of these islands is 5 to 10 feet above high tide; but the bay sides are often less than two feet above high water and regularly flooded. Erosion threatens the high ocean sides of these densely developed islands and is generally viewed as a more immediate problem than inundation of their low bay sides. Many ocean shores are currently eroding 1 to 4 feet per year. Coastal engineers generally estimate that a 1 foot rise in sea level will cause the shoreline to erode an average 0.5 to 1 feet from New England to Maryland, 2 feet along the Carolinas, 1 to 10 feet along the Florida coast, and 2 to 4 feet along the California coast, over a wide variety of terrain. In specific vulnerable locations, which often correspond to wide, flat sandy public recreation beaches, a 1 foot rise in sea level may cause the sandy beach to retreat by as much as 40 to 60 feet. Because many US recreational beaches are less than 100 feet wide at high tide, even a 1 foot rise in sea level would threaten homes in these areas. A study by the Federal Emergency Management Agency estimated that about 25 percent of all buildings within 500 feet of the U.S. coastline will be taken by erosion in the next 60 years.
The historic Cape Hatteras Lighthouse in North Carolina was built in 1870 on a strip of sand more than a quarter mile from the water's edge. It was thought to be safe from the sea's force. For almost a century, it was. But by the 1970s, the slow rise of the ocean's waves threatened its foundation. The lighthouse was a mere 160 feet from the water's edge. To preserve the landmark, the nation's tallest brick lighthouse, the National Park Service moved it more than half a mile inland--an engineering feat that took a decade to plan and cost taxpayers a whopping $10 million.
The Montauk Point Lighthouse in New York is experiencing similar problems and a decision to further armor it or move it will have to be made soon.
Beach-front homeowners at many locations along our coasts are being threatened by rising sea levels, increased erosion and damage from hurricanes and major storms. Their decision to build close to the ocean, combined with natural and human-induced erosion, has increased calls for either coastal armoring or massive, expensive and temporary beach fill projects.
Along sandy beaches, like wetland shores, property owners often erect structures to halt erosion. Although these sea walls protect property, they can eliminate beaches, particularly bay beaches, which are usually less than 10 feet wide. Beaches are used for fishing, recreation, transportation, and landing small crafts, in addition to their environmental importance. In most states, the beach below mean high water is owned by the public. To protect these public assets, several states have adopted policies to ensure that beaches, dunes, or wetlands are able to migrate inland as sea level rises. Some states prohibit new houses in areas likely to be eroded in the next 30 to 60 years. Concerned about the need to protect property rights, Maine, South Carolina, and Texas have implemented some version of "rolling easements" in which people are allowed to build, but only on the condition that they will remove the structure if and when it is threatened by an advancing shoreline.
Changing climate also increases the vulnerability of coastal areas to flooding. A higher sea level raises the flood level from a storm of a given severity. A 3-foot rise in sea level (for example) would enable a 15-year storm to flood many areas that today are only flooded by a 100-year storm. A 1991 report by the Federal Emergency Management Agency estimated that a one foot rise in sea level would increase the size of the 100-year floodplain in the US from 19,500 square miles in 1990 to 23,000 square miles, and increase flood damages (and hence flood insurance rates) by 36 to 58 percent.
Coastal flooding is also exacerbated by increasing rainfall intensity. Along tidal rivers and in extremely flat areas, floods can be caused by storm surges from the sea or by river surges. Higher sea level and more intense precipitation could combine synergistically to increase flood levels by more than the rise in sea level alone in much of coastal Louisiana and Florida, as well as port cities along major tidal rivers, such as Alexandria, VA; Portland, OR; Philadelphia, PA and Washington DC.
If hurricanes become more severe or frequent due to global warming, flooding would further increase; this appears to be the short-term trend, but that link has not been conclusively demonstrated. The U.S. is currently crossing the peak (we hope) of a multi-decadal natural cycle of increased hurricane activity. Therefore the effects of global warming have and will continue to combine with natural cycles to increase damage from storms and flooding.
Finally, rising sea level tends to increase the salinity of both surface water and ground water. New York, Philadelphia, and much of California's Central Valley get their water from portions of rivers that are slightly upstream from the point at which the water is salty during droughts. If salt water is able to reach farther upstream in the future, then the existing intakes would draw salty water during droughts. Higher estuarine salinity has also been cited as a cause of declining oyster harvests in Chesapeake and Delaware Bays, and as a cause for wetland loss in Louisiana, Florida, and Maryland.
The type of aquifers that are most vulnerable to rising sea level are those that are recharged in areas that are currently fresh but which could become salty in the future. Residents of Camden, New Jersey and farmers in central New Jersey rely on the Potomac-Raritan-Magothy aquifer, which is recharged by a portion of the Delaware River that is rarely salty even during severe droughts today. This part of the river and thus the aquifer would become salty more frequently if sea level rises a few feet or if droughts become more severe. A second type of vulnerable aquifers are the shallow coastal aquifers found on small islands. Freshwater is lighter than salt water, and hence the fresh water "lens" floats on top of the salty groundwater. In some types of aquifers, for every inch the sea rises, the freshwater lens loses 40 inches of depth. Although few communities in the United States obtain their water from these types of aquifers, important parts of such coral atoll nations as the Maldives and Vanuatu could lose their primary water supplies with even a two foot rise in sea level.
Warmer waters, more acidic oceans and stronger storms are taking their combined toll on coral reefs. Loss of coral reefs would translate into huge economic losses in coastal regions dependent on reefs--they provide about $375 billion each year in food and tourism income. (U.S. Commission on Ocean Policy)
Severe damage to reefs is also an ecological catastrophe. Coral reefs are sometimes called "rain forests of the ocean" because they are home to a rich diversity of marine life such as reef fish, turtles, sharks, lobsters, anemones and sponges.
Corals get both their food and their spectacular color from tiny algae called zooxanthellae that live in them. Corals are very sensitive to temperature and thrive within a narrow range of heat and cold. An increase of just 1.8 degrees Fahrenheit above the typical maximum summer temperature can cause corals to expel their algae, or "bleach." After prolonged bleaching, they often die.
A massive bleaching of corals occurred during one of the warmest 12-month periods on record, in 1997 and 1998. About 16 percent of the world's reefs suffered severe damage, and thousand-year-old corals perished.
Coral reefs are threatened by many other causes than temperature, but most of those other threats, from siltation and polluted runoff to simple breakage by boats and anchors, are also man-made. Continued increases in ocean temperature could make mass bleachings a frequent event.
Coral reefs face another threat related to global warming: carbon dioxide (CO2) pollution. Carbon dioxide is the main heat-trapping gas that causes global warming, but that's not the only damage it does. A report by the U.K.'s Royal Society found that the increased levels of CO2 in the ocean are making it more acidic.
When CO2 dissolves in ocean waters it produces carbonic acid, which lowers the overall pH of the ocean. The lower pH values cause the limestone (calcium carbonate) structures of coral reefs and seashells to dissolve. As waters become more acidic, coral reefs and other marine ecosystems could suffer. The Royal Society's panel of scientists report that acidification will hurt tropical and subtropical reefs the most, but cold-water corals are also in danger.
Other studies have shown that acidification adversely affects certain types of plankton, tiny animals which are the base of the ocean food chain. Larger animals from salmon to whales, including many marine life forms that are important sources of food or other economic activity for mankind, are likely to suffer declines as plankton decreases.
Since acidification is "irreversible in our lifetimes," the Royal Society's authors say, "the only practical step is to reduce emissions of carbon dioxide as quickly as possible to minimize large-scale, long-term harm to the world's oceans and marine ecosystems."
Corals and plankton are sensitive but also very resilient--if conditions are right. If we can reduce some of the other direct stresses from human activities on coral reefs, like pollution from diffuse sources, that may also enable reefs to cope better with threats like climate change. Creating more protected areas for coral reefs may help them better withstand the rigors of too-warm water and be less vulnerable to extinction.
So, what can be done about global warming? What can Surfrider members, Surfrider activists and the average citizen do to make a difference? As it turns out, there's a lot we can do both individually and collectively than can help "turn the tide."
Since the bulk of greenhouse gas emissions come from automobiles and energy generation, it is simply no longer possible to discuss the health or economic activity of our world's ecosystems without discussing transportation and energy policy.
There are multiple benefits that come along with most of the following actions. They not only address the problem of global warming, but they also help to increase our energy self-sufficiency, reduce air pollution and save you money. So these actions make sense even if global warming were not an important issue.
When it comes to global warming, how and what we drive are two of our most powerful choices. Transportation is the biggest source of U.S. carbon dioxide emissions, more than factories or homes.
Home energy accounts for 21 percent of America's global warming pollution. If we make smart choices, we can cut more pollution than the entire emissions of over 100 countries!
For very technical discussions, often refuting the statements of those who doubt global warming, see: RealClimate.org.