Fear Mongering Floods

published in the Pacifica Tribune June 12, 2019

What’s Natural

Politics Distorts the Science of Floods

At the confluence of the Missouri and Mississippi Rivers, native American “mound builders” built Cahokia, the largest city in pre-Columbus America. The purpose of their mounds is still debated. Were the mounds refuges from frequent floods, strategic defenses from hostile attacks, or monuments to ruling elites? I suspect all of the above. During warmer and more arid times with minor flooding, Cahokia’s population expanded. By 1250 AD its population equaled contemporary London or Paris. Charles Mann wrote about Cahokia in his superb book  1491 , “the kings who gained their legitimacy from claims to control the weather, would face angry questions from their subjects” when the catastrophic floods returned.  Indeed, as severe flooding increased, Cahokia was eventually abandoned.

Great Flood of 1927 Mississippi River

Eerily, in the wake of the 2019 Mississippi River Valley flooding, politicians are similarly telling flood victims that their climate policies can also control the weather. Washington’s Governor Inslee tweets, “For the people of Davenport, Iowa, climate change is personal. It’s destroying their homes, harming their communities, and hurting their livelihoods. We must defeat the climate crisis to protect our fellow Americans.” Senator Warren tweeted, “the consequences of climate change are severe, and they are already affecting places like Burlington, Iowa. We have a moral responsibility to act.”  But these politicians ignore the science and long history of the Mississippi’s floods. 

Investigating causes of Cahokia’s abandonment, scientists uncovered natural climate cycles 

governing the region’s flooding. Large floods were common between 300 AD and 600 AD.  Then between 600 AD and 1200 AD more arid conditions prevailed. But after 1200 AD severe flooding returned. Natural ocean oscillations can explain alternating patterns of dry and wet periods. So accordingly, the Intergovernmental Panel on Climate Change (IPCC) expresses low confidence regards any global warming effect on modern flooding.

Over the Atlantic Ocean exists a large and somewhat permanent atmospheric pressure system named the North Atlantic Subtropical High (NASH), or Bermuda High. Its clockwise rotation critically effects the climate of the eastern United States. NASH is the reason the eastern United States experiences very humid summers in contrast to the dry west because on NASH’s western edge, warm moist air from the south is pumped northward. More importantly, NASH regulates regional droughts and floods. NASH naturally shifts locations over decades driven by natural ocean oscillations like El Nino. When NASH shifts further to the west, more moisture from the Gulf of Mexico is pumped into the Great Plains causing more floods. When shifted further east, the Midwest suffers more droughts. 

Non-scientific journalists and media talking heads falsely insinuate recent extreme flooding is due to global warming. They parrot a single fact that “warmer air can hold more moisture”. Although true, that fact is grossly misapplied. The earth’s warmest air temperatures happen over deserts, but there the air is bone dry. The key to extreme rainfall is not temperature, but how much moisture is transported from the oceans to the land. During cooler times, severe Mississippi Valley floods were observed in 1809, 1829, 1844, 1851, 1874 and 1882. The Great Flood of 1927 is considered the Mississippi Valley’s greatest modern flood. Due to the transport of excessive moisture from the Gulf, average rainfall nearly doubled in 1927. 

In contrast to global warming predictions, the Mississippi River Valley also experienced below average winter temperatures and above average snowfall in early 2019. The National Weather Service issued early warnings that the melting snow could cause flooding. They further warned the frozen ground and saturated soils wouldn’t absorb the excess water, additionally swelling streams and rivers. 

So many farmers are rightfully rejecting the politicians’ climate claims. Instead farmers blame the Army Corps of Engineers for breached levees and improperly managing levee systems. Levees had seduced people to move into the flood plains. People assumed those levees would always be maintained. But worse, the levee systems unintentionally elevated flooding probabilities.

Each year high water levels from snowmelt and spring rains cause rivers to approach flood stage. Excess water would normally get stored on natural floodplains, minimizing downstream floods. But when levees deny a river’s access to its flood plains, higher volumes of flood water get shunted downstream. Instead of allowing flood waters to spread out, levees narrow a river’s channel width, forcing the river to rise much higher than normal. Thus researchers had warned, “river engineeringhas elevated flood hazard on the lower Mississippi to levels that are unprecedented within the last five centuries.”  

Blaming CO₂climate change only misguides attention from these real problems. If politicians sincerely hope to promote wise flood protection, they better educate themselves regards natural climate cycles and the unintended consequences of separating rivers from their flood plains.

Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU

and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism

Contact: naturalclimatechange@earthlink.net

Cycles of Rapid Climate Warming

Published in the Pacifca Tribune May 28, 2019

What’s Natural

Cycles of Rapid Climate Warming

The globally averaged temperature rose 1.5°F from 1880 to today. Various narratives suggest the rise since 1950 was driven by increasing concentrations of CO2. The rising temperature before 1950 was considered natural. Since 1990, Arctic temperatures rose 2 to 3 times faster than the global average. So, are rapidly rising Arctic temperatures evidence of an impending climate crisis? 

Astute students of climate history recall rapid Arctic warming has happened often and naturally. During the last Ice Age when CO₂ concentrations were just half of today’s, 25 abrupt warming eventshappened. Arctic temperatures rose 9°F, and sometimes as much as 14°F in just 40 years. These rapid warming episodes are now called Dansgaard–Oeschgerevents (D-O events) in honor of the researchers who first detected them in Greenland’s ice cores. These D-O episodes affected global climate, changed ocean currents along California’s coast and altered the range of European forests.

What caused such abrupt warming? Basic physics dismisses changes in greenhouse gases or solar insolation because neither radiative effect induces such rapid warming. The most reasonable explanation suggests episodes of ventilating heat, that had accumulated in the Arctic Ocean, rapidly warmed the air. 

The notion of stored heat in a freezing Arctic Ocean seems unfathomable to many laypeople. But it is scientifically well documented.Tropical Atlantic waters experience intense heating and evaporation. This results in warm salty water that is relatively dense. The Gulf Stream and its branching currents then transport that warm water northward. Because the water is salty and dense it sinks below colder and fresher surface waters as it approaches the Arctic Ocean. As a result, there is a layer of warm Atlantic water stored at depths between 300 and 2,700 feet below the Arctic Ocean’s surface.Arctic researchers report, “the total quantity of heat is substantial, enough to melt the Arctic sea ice cover several times over.”

Warm Atlantic Water in the Arctic Ocean

Sea ice and a layer of cold fresh water normally inhibit subsurface heat from ventilating to the atmosphere. But as the incoming heat increases and accumulates, the warm Atlantic Waters can eventually melt the overlying ice cover. Other times, changes in the direction of Arctic winds will blow sea ice out into the Atlantic, as it did in the late 1990s. Either way, without insulating ice, a burst of heat ventilates from the ocean and warms the atmosphere. 

Recently, anthropologists studying past Arctic cultures found the pre-Dorsett culture periodically abandoned then recolonized the Arctic coast as changes in sea ice affected temperatures. When sea ice covered coastal waters for 2 months longer than today, temperatures became 3-7°F cooler. Arctic people then abandoned the coast and moved south. A few hundred years later they re-colonized the coast when periods of open water, lasting 4 months longer than today, allowed heat to ventilate and raise temperatures 10°F warmer than today.  Such changes alternated over several hundred years. And that raises the question, is the Arctic still experiencing similar cyclical warming?

Over the past several hundred years, melting Arctic sea ice corresponds with observed periods of increased intrusions of warm Atlantic waters. The dramatic Arctic warming during the 1920s and 1930s corresponded with increased intrusions of warm water accompanied by Atlantic fish species normally found further south. As the 1922 newspaper clipping reveals (see above), the warming of the Arctic was so dramatic it raised concerns the frigid Arctic would soon be converted to a warmer “temperate zone”. 

Arctic 1922

When warm water inflows began retreating around 1950 so did the Atlantic fish. Sea ice then increased.  Such cycles have been recorded infishery data for hundreds of years. The most recent cycle of melting Arctic sea ice likewise coincided with intruding warm Atlantic waters with patterns of invading fish very similar to the 1920s-1930s warming episode.

So, we are now in the midst of an instructive natural experiment. If the loss of Arctic sea ice and warmer temperatures are due to rising CO₂concentrations, we should soon see a total loss of Arctic sea ice as predicted by some climate scientists. In contrast, if natural oscillations are controlling intrusions of warm Atlantic waters, Arctic sea ice will soon rebound. Indeed, a recent shift in ocean oscillations is now decreasing warm water intrusions. Temperatures should fall as less heat ventilates into the atmosphere. Based on earlier 20^thcentury patterns when lost sea ice rebounded in the 1960s and 70s, Arctic sea ice should begin rebounding by the year 2030. But then again, warmer temperatures did last for 300 years during cycles a few thousand years ago. Either way, natural climate cycles predict Arctic temperatures will not experience further accelerated warming. We will soon see which theory is most accurate within the coming decade.

Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU

and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism

Contact: naturalclimatechange@earthlink.net