The World We Used To Know

Our fourth rainy weather system of the spring (and almost summer) has arrived today.

I bet if you ask your children or your friends, or even your parents, they won’t remember a time when it rained periodically from after Shavuot until the middle of June. They won’t remember it because the world we live in today is not the world we grew up in or one we’re familiar with.

In fact, as Yaakov Cantor of our (ironically named) “Israel Winter Weather” group noted: “In the past 70 years, there are no recorded instances of three consecutive rain events late May into June.”

“There have been a few instances of two events, but those were mainly cold fronts, not rain events with very warm temperatures and tropical moisture like these. Also, having these rain events associated with thunder is quite rare so late in the spring.” Moreover, he notes that “having measurable rainfall in the southern Negev and Arava is very rare. [There were] only two other instances in the last 70 years”

So what’s different about our weather pattern? In brief, Yaakov sees three reasons  for our unusual storminess since late May:

1) El Nino is enhancing the southern/subtropical jet stream from the eastern Atlantic to north Africa/Middle East

2) There is record warmth in the eastern Atlantic leading to a more intense jet stream and moister atmosphere than usual flowing from the eastern Atlantic into the Mediterranean.

3) There is delayed South Asian monsoon preventing the usual ridging from establishing itself across the Middle East/eastern Mediterranean.

In short, ocean temperatures have warmed substantially in response to warming of the atmosphere (associated with elevated greenhouse gases). It is these elevated ocean temperatures and their spatial variations that have large impacts on our weather.

Why has all this happened? Well, the reason is us — and how we live our lifestyles.  Granted, we need energy to power our society and our economies. Yet, a lot of effort and money was spent hindering the enactment of laws that would have required greater energy efficiency and concurrently not enough money has been spent on developing new technologies to power our world without producing Carbon Dioxide and Methane (two major greenhouse gases). Too many forests have been burned down and now are burning because temperatures have warmed in places where historically they were not conducive to wildfires. As Stephen Pyne — a professor emeritus of at Arizona State University said: ““We are creating the fire equivalent of an ice age.”

The problem we’re facing as a society is that we’re being deluged by simultaneous weather related catastrophes. They are the result of a number of weather anomalies (extremes) occurring at the same time, as nicely summarized in this Washington Post article. More frequent years with weather related catastrophes that have caused great cost to our society (see our featured image).

As noted by James Hansen in his most recent post, Carbon Dioxide levels have risen to levels that in the past left Antarctica unglaciated. While this is alarming by itself, one should keep in mind that in the past carbon dioxide levels generally rose or fell based on the air temperatures. These air temperatures in turned varied because of variations in the earth’s orbit.

Thus, as any naysayer will tell you, there have been and always will be substantial changes in the earth’s climate, regardless of how Humans interact with the world we live in. This is correct, but never before have we humans engaged in climate “engineering;” nor do we truly understand the potential consequences to our society and our ability to survive on this planet.

Hence, our need for numerical climate models to help us elucidate society’s  potential impacts on climate (see Figure 10.4, here, for example) given the natural  long term climate changes. They are such that a large part of the world can be covered by ice (and Israel by deciduous forests) or a planet where the dinosaurs thrive. Given our current “location” in the climate pendulum, the models predict a steady rise in temperatures and continued disruptions to the typical climate state of the last 50 or so years.

Hence, we shouldn’t and can’t assume that “everything will be okay.” Instead, we need to create incentives to innovate and transition our society to a cleaner and more resilient path.