Answers to those questions in your head you think everyone understands but you (e.g., How is more snowfall a sign that the earth is warming?)

August 31, 2017
Climate change

I commiserate with your confusion. Despite being a scientist, I am not an environmental scientist and there was a steep learning curve for me going into this space professionally. I get it now. Please allow me to clarify a few key misconceptions that always come up in conversations with my family/friends (I won’t name names).

1. Droughts and heavy rainfall are both impacts of climate change?

Warming temperatures and air are causing more extreme climate conditions included extended periods of drought and heavy periods of rainfall. Higher temperatures have lead to increased rates of water evaporation. Even in areas where precipitation does not decrease, increases in surface evaporation and loss of water from plants lead to more rapid drying of soils. As soil dries out, a larger proportion of the incoming heat from the sun goes into heating the soil, resulting in hotter temperatures under drier conditions.

Heavier rainfall results from increasingly warmer air, which can hold more water vapor than cooler air. This extra moisture is available to storm systems, resulting in heavier rainfalls. We need to recognize that both wet and dry extremes will increase in intensity, frequency, and duration.

2. Shouldn’t sea level rise be the same increase globally?

Just as the surface of the earth isn’t flat, the surface of the ocean isn’t flat. The absolute water height of the ocean is higher on the U.S. east coast than on the U.S. west coast. When seal level rise (SLR) is referred to in the singular, it refers to the average global sea level rise trend.

Over the last century, global average sea level has been approximately eight inches. Historical and future sea level change has not and will not be the same everywhere, and in fact, varies greatly. For example, in the U.S., New Orleans has had forty-six inches of SLR while Los Angeles has had only four. These differences are mostly due to land subsidence (i.e., land sinking) or uplift, which increases or reduces the global average sea level change.

3. Despite increasing water from melting glaciers and ice sheets, we still have less water?

For anyone who’s swallowed seawater, it should be no surprise that filling your cups from the ocean is not an option. Melting ice increases sea level rise, which may seem to imply an increase in water supply, but the energetic demands and financial costs of desalination techniques (which would be required to actually use the “extra” water) are far from being commercially viable.

As ocean levels rise, saltwater intrusion will contaminate drinking and irrigation water supplies, impacting not only surface water, but also seeping into aquifers and other groundwater sources. Saltwater intrusion will penetrate farther inland than in the past, and both current measurements and modeled projections suggest that drinking water losses either have occurred or will soon manifest in numerous locations around the world. For example, it is expected that Bangladesh will experience a shortage of potable drinking water by the year 2050.

In edition to being infeasible for human consumption, saltwater is devastating for agriculture. Twenty percent of the world’s irrigated farmland is already contaminated with salt. Saltwater for a farmer means certain crop failure.

4. How did we not have more notice that Harvey was coming? What have scientists been doing this whole time?

Scientists widely agree that the pace of warming is tens or even a hundred times faster than at any known period in the last five hundred million years of geologic history. This has created conditions for which there is no comparison historically. The earth’s temperatures and climate events were largely stable for the past several millennia, only recently changing course in the anthropogenic period (or period of man-made climate change). Therefore historical data does not exist from which to make comparable predictions.

5. How is more snowfall a sign that the earth is warming?

Snowfall and rainfall cascade to the earth as forms of precipitation. Snow falls instead of rain because of the temperature at the time of precipitation release, NOT because of a decreasing global temperature trend. Increased precipitation is caused by more water being evaporated from the oceans due to warmer ocean temperatures. Despite it feeling counterintuitive, increased snowfall has actually been an offshoot of warming oceans.

Oceans have warmed by 1.5 degrees Fahrenheit (1 degree Celsius) this century. The rate of warming is increasing, resulting in record rainfall (and snowfall when the temperature is appropriate) events worldwide.

6. Why can’t we reverse it?

No amount of collective global effort can change the fact the sea level will rise. This is because the melting that has already taken place of the earth’s glaciers and ice sheets cannot be undone before the impacts are felt worldwide. In fact, it will take centuries or even millennia to reverse the extent of melting that has already taken place. We must accept that SLR is a permanent new fixture that will permanently change the ocean’s height for generations to come, and subsequently reshape continents, as we know them now.

For answers to more questions, please email me directly and I will aim to address them in a future blog post.

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