A Rainy Day

A cool, humid day. This morning dawned red; now the lowering clouds have led to persistent light rain. The other day we had a thunderstorm and the first appreciable rain in many weeks.

The drought conditions here have been reclassified from moderate to severe and the natural world is thirsty. Our farmers’ markets show the impact of the drought; our usually abundant options being much reduced. The absence of rain impacts farmers in many ways. the soil is so dry it crumbles and blows about and the wildlife is so desperate for food they break through barriers to get into fields; a farmer acquaintance of ours has lost a thousand pepper plants to the deer.

Over the weekend we got together with family around the backyard grill. The evening was hot and humid and we were visited by a few mosquitoes; mosquitos here carry a couple of very dangerous viruses and are to be avoided if possible.

While attending the grill we got into a conversation about the drought and found ourselves comparing our woes to those of folks out west. Someone suggested that our local drought is not that severe in comparison which is both true and false.

Much of the western US is characterized by reduced rainfall regimes and ecosystems are resilient in the face of cyclic drought. Unfortunately the present severe drought is of a historically rare duration and there is little relief in sight. On a positive note, back home in the southwest they had an extended monsoon this summer which, while not drought breaking, brought desperately need rains to the high plateau.

This morning I read about the ongoing drought in Europe, a disaster rarely covered by media in the US. The drought there follows a spring of flooding; this is very much within the footprint of climate change in which temperate zone winters are warmer and wetter than the historical norms and the summers hotter and dryer.

The impacts of drought are ecosystem dependent: regimes acclimatized to cool temperatures and frequent rainfall suffer badly in extended drought and reduced rainfall can have severe long term impacts. What might seem like plentiful rainfall to someone living on the plains or in much of the west can create severe drought here in the northeast. From an ecosystem perspective its all about the historical norms.

In grad school I became fascinated by the intersection of diversity, complexity, and stability in ecosystems. In general ecosystem stability is a measure of adaptation to long term norms. Arctic biomes are adapted to short growing seasons and long periods when water is frozen and not available as a resource. These systems are relatively simple, yet highly interconnected, and are characterized by boom and bust cycles in the terrestrial food chain and thus, animal species abundance.

Ecosystems in the Amazon on the other hand are generally governed by seasonal monsoons alternating with dry periods. Temperature and available moisture are determined by forest density with large clearings being both much warmer and drier than the adjacent forest. These ecosystems are less dependent on periodic disturbance and conditions can be essentially stable over very long periods of time. This stability has allowed for systems to become immensely complex, diverse, and interconnected.

Sadly, rising global temperatures, shifts in seasonal weather patterns, and increasing forest fragmentation and deforestation have served to greatly reduce regions of viable forest in the Amazon basin while increasing drought conditions in the region. This has resulted in reducing both diversity and complexity to the extent that the system as a whole may be nearing collapse.

In the arctic milder winters have led to increased free surface water in winter, which severely hampers the migration of key species such as caribou, increased sea ice melt which impacts polar bear and sea mammals, and drier conditions in spring and summer which has increased the thawing of the permafrost and the incidence of intense wildfires. In an ecosystem evolved around winter the stresses resulting from these changes also threaten ecosystem collapse.

As our planet warms each ecosystem is stressed in ways unique to it. Our news media are ill equipped to convey the complexity of these stressors or the unique conditions impacting regional and local ecosystems. Comparing impacts across systems is at best misleading and serves to underrepresent the immensity of local, regional, and global changes and their impacts.