Banner photo by Don Hebert, showing shoreline erosion in Anegada, BVI following a hurricane

Climate, Weather & Climate Change

Before we dive into the scientific evidence supporting anthropogenic global warming and climate change, let’s define some basic terminology.

Weather: is the current atmospheric conditions (short term) such as temperature, humidity, clouds, precipitation, wind, etc.

Climate: refers to the average weather patterns of a region in the long term, typically spanning over 30 years. Climate data not only includes averages but also accounts for seasonal variation and probability of extreme weather events.

Climate Change: refers to changes in global climate patterns. The current climate change is a global warming caused by human emissions of heat trapping greenhouse gases.

Climate sensitivity: refers to the uncertainty in predicted temperature change and further impacts that will result from emissions of greenhouse gases. Unfortunately as temperatures rise as it promotes “positive feedback loops” that create further instabilities in global climate. An example of a feedback loop is as the temperature increases, the polar ice caps and glaciers melt, less sunlight is reflected back, so temperature warms further.

Climate Change Impacts: refer to the effects (positive and negative) on humans and other life. While some impacts are being experienced today, impacts usually refer to future scenarios based on the continuation of current emission trends. These impacts include sea level rise, increased extreme weather events, changes in precipitation patterns, and loss of habitat and biodiversity.

The enhanced Greenhouse Effect

The greenhouse Effect

Greenhouse gases, such as water vapor, carbon dioxide, and methane, exist naturally and trap heat in the atmosphere in a process known as the greenhouse effect. The greenhouse effect gives our climate stability and allows our planet to support life. Usually there is a small atmospheric window in which some heat can escape, but as we continue to emit greenhouse gases by burning fossil fuels, land use change, industry and agriculture we risk narrowing this window and trapping too much heat.

Why is Carbon Dioxide so important?

Did you know that the most important greenhouse gas is actually water vapor? H2O captures 36-72% of radiation heat depending on the local humidity. So then why is everyone talking about carbon dioxide? The issue with carbon dioxide is that it remains in the atmosphere for a really long time. In order for Co2 to be removed from the atmosphere it must dissolve in the oceans, be absorbed by the biosphere, or eventually turn into compounds such as calcium carbonate. And, 20% will remain in the atmosphere forever. These process do not happen quickly meaning that the Co2 released into the atmosphere now will remain there for thousands of years to come.

What’s different about modern climate change?

In modern society, succeeding the Industrial Revolution of the 1800’s, human emissions of greenhouse gases are due primarily to burning fossil fuels. Although in the past, during the age of dinosaurs, earth has had even higher concentrations of carbon dioxide, climate change today is occurring at the rate so alarmingly fast that the earth and its species will have immense difficultly adapting to the extreme changes.

Human sources of greenhouse gas emissions

As mentioned previously, climate change is caused by human emissions of greenhouse gases. The primary source is due to burning of fossil fuels.

When hydrocarbon fossil fuels such as coal, petroleum and natural gas are combusted in air. The energy we utilize is created by breaking the bonds of hydrogen and carbon. Once those bonds are broken the carbon of the fuel and oxygen of the air combine to form Co2 which is emitted from smokestacks or tailpipes. The higher the carbon per hydrogen ratio in the molecule, the more Co2 emissions.

We utilize fossil fuels in almost every aspect of modern life. We use them for electricity production in thermo-electric power plants. We also utilize fossil fuels to create heat for buildings and industrial processes or as a byproduct of production. We emit greenhouse gases during transportation by burning of gasoline or diesel in cars, buses, trains and the biggest emitter air travel.

We also emit greenhouse gases without burning fossil fuels. During agriculture production, especially cow production or rice farming, we emit greenhouse gases such as CO2 and methane. Finally we emit greenhouse gases through deforestation and land use change by removing trees and forests that would have otherwise acted as carbon sinks.

Climate Change Impacts for USVI

The majority of climate change impacts in the Caribbean are related to water resources and are mentioned in more detail in the previous section on WATER. Climate change impacts on water in the Caribbean are predicted to result in an average temperature rise, more hotter days (over 95F), an overall decrease in annual precipitation, an increase in flooding and droughts, more intense hurricanes and other extreme weather events, sea surface temperature rise, ocean acidification, sea level rise, and saltwater intrusion and inundation. Information on climate change impacts has been taken from the U.S. 4th National Climate Assessment (2018).

Diagram taken from Chapter 20: U.S. Caribbean of the 4th National Climate Assessment (2018) regarding climate indicators and climate impacts on Puerto Rico and the U.S. Virgin Islands.

Climate Change Adaptation

Climate Change Vulnerability: indicates a particular regions ability to cope with the impacts of climate change, based on social, economical and environmental factors. Small island developing states (SIDS) are considered to be the most vulnerable to the impacts of climate change due to the level of impacts, limited resources, a developing and isolated economy, the small size of the region and a low adaptive capacity,

Adaptive Capacity: is based upon a regions ability to adapt to changes ideally with minimal threats to local culture, lifestyle, economy and the environment. Although many consider small islands to have a low adaptive capacity due to the isolated and small nature of the region, it is a highly debated topic.

Those who argue for a low adaptive capacity point out that the economy is highly dependent on climate sensitive industries such as tourism and agriculture, the threat of sea level rise to the nation’s sovereignty, that a single extreme weather events can drastically affect the entire region’s economy and well-being, and due to its isolated nature recovery and aid is difficult to receive.

Others consider islanders will be incredibly resilient to future climate change impacts to as proven by past experiences. As island regions are already difficult to inhabit, experience says that island systems are incredibly well adapted due to close communities, experience with living in isolation without receiving outside aid, and experience in withstanding extreme weather events such as tsunamis and hurricanes. Of course there is always room for improvement and many island nations today are working to recognize their vulnerability and improve upon their strengths.

Climate Change Mitigation: are strategies, executed at the individual, regional or global scale which decrease, stop or store our global emissions of greenhouse gases in order to limit the drastic consequences of climate change. The benefits of climate change mitigation strategies are shared globally.

Climate Change Adaptation: are strategies, executed on the individual and local level, which abate the negative impacts of climate change and capitalize on positive impacts on a local or regional scale. These strategies can range from building infrastructure to protect regions from flooding or storm surges, from planting different crops to adapt to changing temperatures or conserving or rejuvenating ecosystems that provide essential services to the region.

In the past many did not support climate change adaptation in fear that only countries that could afford it would use this tactic without employing mitigation strategies, leaving the developing nations of the world to deal with the impacts of climate change. However today, the sentiment is we are already experiencing the impacts of climate change and therefore all actions should be taken to both mitigate and adapt to climate change to minimize tragedy.