Climate Change Basics

Throughout the earth’s five-billion-year history, there has always been climate change. The geologic record, which reveals the ebb and flow of glaciers, the rise and fall of oceans, the evolution and demise of dinosaurs, tells us that. What is new, however, is the direct role that humans have played in climate change since the Industrial Revolution  began in the late 18th century.

Humans have long used fires to cook meals, provide light, warm their houses, huts and caves. Wildfires have long raged across grasslands and forests, whether caused by lightning strikes or set by early peoples to improve conditions for hunting and grazing. All fires, large and small, release gases such as carbon dioxide and methane that contribute to climate change. But the advent of mechanized industry, which relies heavily on burning coal, oil and natural gas, has fueled greenhouse gas emissions  of enormous magnitude. After two centuries, human-caused air pollution has overtaxed the earth’s ability to cleanse its atmosphere and reset the climate to cooler norms.

Today, when we talk about climate change, it’s not the sort that drove T-Rex to extinction. Rather, it’s about modern climate change, also known as anthropogenic or human-caused climate change. Modern climate change isn’t the same as geologic climate change. It warms the Earth much faster than natural climate processes do. Overwhelmingly, it’s fossil fuels burned by humans that drive the negative effects of climate change. In little more than 200 years, the machinery of modern civilization has altered the earth’s climate in ways that our ancestors would’ve have found unthinkable.

Modern climate change has already changed many aspects of our environment. With warmer temperatures, we see more frequent droughts, rising sea levels and severe hurricanes. For all that, humans still have the potential to reduce the extent of climate change through mitigation  efforts. Yet since we can’t stop climate change in the near-term, we must adapt to climate change  now and for the foreseeable future.

When some people talk about climate change, they use the term “global warming,” which was more common 10 to 20 years ago. Global warming does indeed describe the higher average temperatures that have been recorded since the late 1800s. However, the term climate change better captures the nuanced nature of this phenomenon. In the north, for instance, you may hear someone say during a cold snap, “Hey, we could really use some global warming about now!” In fact, unusually cold weather — along with unusually hot weather, and prolonged drought followed by severe rainstorms — can all be driven by climate change. While such singular weather events have always occurred, the impact of climate change has made them more frequent and severe than before.   

Land trust staff need a good working knowledge of climate change, but they’re not expected to be climate scientists. Instead, they must deal with the impact of climate change, even in places where climate change remains a controversial topic. (A good reason for land trusts to examine how they communicate about climate change.) Discussions about phenology offer a neutral way to find common ground around climate change. Phenology refers to the timing of seasonal events, such as when trees’ leaf out and migrating birds return — natural conditions that people can see in their own backyard. The impact of phenological changes include:

• Misalignment in lifecycle events of species that rely on one another. (Caterpillars, a prime food source for nesting birds, may appear before migrating birds arrive.)

• Earlier arrival of warm temperatures may cause many trees and flowers to blossom earlier, even as the danger of frost lingers. For plants highly susceptible to frost damage, this can greatly reduce fruit, nut or seed production.

• Increased risk of drought, due to earlier snow-melt and longer summers.

• Greater impact by pests and disease that feed and breed earlier in the season. Some pest species will also increase in numbers, due to milder winters that reduce die-off so that more pests survive until spring.

Along with phenology, shifting seasons can trigger otherer climate change impacts, such as earlier, more extensive floods. Along with their profound impact on species and ecosystems, these changes will affect human activities — such as farming, ranching, logging, and fishing — for those whose livelihood depends on them.

Clearly, climate has a major environmental influence on ecosystems. Along with changing the timing of migration, high temperatures may force some species to seek cooler habitat at higher latitudes or elevations. Meanwhile, at river mouths where freshwater normally flows into the ocean, rising sea levels may allow saltwater to intrude upstream into freshwater systems. The contamination that results can kill off predators or prey that were critical to the existing food chain.

Along with rising temperatures, climate change can also influence the amount, distribution and timing of precipitation events. Such is the paradox of climate change. It can make precipitation fall less often, yet cause more intense snow or rainstorms when it does fall. We see that in the western United States, where the frequency of large wildfires and the total acreage burned has steadily increased.

Wildfire was once – and could again be – a healthy part of a western forest ecosystem. But, a phalanx of climate-driven forces has disrupted that. Milder winters mean that pests such as the pine bark beetle can spread and kill trees already weakened by drought. In another climate twist, warmer temperatures spur more frequent thunderstorms; which bring more lightning strikes to kiln-dry forests. Yet sound land trust management practices such as thinning dead trees has been proven to improve forest health and reduce fire risk. So have prescribed fires, which remove excess forest debris that has built up over decades of human fire suppression.

Of course, for those far from salt water, the role that oceans play in climate change can seem a distant threat. Understandable, since rising seas have yet to threaten Milwaukee or Minneapolis. Nonetheless, oceans comprise 71 percent of the earth’s surface and hold 97 percent of its water. And the average global sea level has risen by eight inches in the past century. By 2300, it could rise another three feet or more. As the ocean surface temperatures warm, climate scientists expect the number and intensity of hurricanes to increase. What does this mean for states far from the Atlantic or Pacific? As the coastlines become less habitable, we can expect more residents to move inland to “climate havens” where climate change impacts have been less severe. Namely, in the East and Upper Midwest, where boosting climate resilience will be evermore crucial for maintaining ecological health.

Warmer water temperatures and higher ocean acidity can also result in coral bleaching. When water is too warm, corals will expel the algae (zooxanthellae) that lives in their tissues. This makes the coral turn completely white. Coral can survive a bleaching event, but the stress it undergoes can cause it to die later. As the climate changes, coral bleaching is predicted to become more frequent and severe.

Land trusts have responded to coral bleaching and reef degradation in various ways. Some groups have begun coral restoration projects to promote the biodiversity and long-term resilience of these fragile marine systems. They have also adopted strategic conservation planning to enhance resilience, all of which can reduce the extent of future climate change.

The earth has its own checks and balance that govern its climate. To imagine how that works, think of a glass of milk on a table. Tip the glass a little, and not much happens. Tip the glass a little further, and still not much happens — the milk just sloshes in the glass. But, tip the glass far enough, and the milk will suddenly pour out onto the table. This moment of suddenly changing from one state (milk in glass, dry table) to another state (milk on table) is called a tipping point.

Tipping points are generally preceded by gradual, low-impact changes. (The milk sloshes around, but stays in the glass). Then things occur quickly (the milk spills rapidly onto the table) that cannot be undone. Many climate change scientists believe tipping points will play a role with climate change, and may affect the timing and severity of climate change impacts. For example: 

• The complete disappearance of Arctic Sea ice during the summer months could dramatically change ocean currents in the Atlantic and Pacific Oceans.

• The melting of permafrost could lead to a massive release of methane gas, thus greatly accelerating climate change.

• A longer dry season, precipitated by a temperature increase of just 5-7 degrees Fahrenheit, could cause a rapid die-off of the Amazon rainforest.

When the output of a system affects itself, this is known as a feedback loop. A well-known example that affects climate change is the ice-albedo feedback loop. Ice has a higher reflectivity — albedo — than land or water. This makes ice better able to reflect heat back into the atmosphere than bare land or water. However, because temperatures are rising, Arctic Sea ice is melting more rapidly in the summer months. This exposes more water, and allows the oceans to absorb and retain more heat. This, in turn, increases the likelihood that even more ice will melt during the next summer.

If we are to protect natural and cultural resources in the future, then we must begin planning for climate change impacts today. Some changes are already occurring. We can expect others in the coming decades. Among them:

• Northern areas are projected to become wetter, especially in winter and spring. Southern areas, especially in the West, are projected to become drier.

• Heavy precipitation events will likely be more frequent. Heavy downpours that now occur about once every 20 years may occur every four to 15 years by 2100.

• More precipitation is expected to fall as rain rather than snow, particularly in some northern areas.

• By 2100, the average U.S. temperature is projected to increase by about 4°F to 11°F, depending on emissions scenario and climate model. 

Despite unknowns about the pace and magnitude of climate change, the evidence shows it’s here to stay. Land trusts must understand and account for its impact. They need a basic knowledge of climate change, one rooted in the everyday evidence they see in the lands they protect. By tying the global to the local, they can adopt new conservation practices as needed – and, explain their rationale to landowners. The promise of perpetuity now requires land trusts to place a high premium on climate-informed stewardship. Even if how land trusts manage land today looks far different 10 or 20 years from now.

These are just some of the impacts that already influence the conservation priorities of land trusts nationwide. By learning more about current and predicted climate change patterns, land trusts can do more to weather the face of a changing climate.