The Inspired Rationalist launched in August with a lengthy post about climate change. Then, in October I spoke at length with Dr. Brenda Ekwurzel, the Director of Climate Science for The Union of Concerned Scientists. The first part of that interview addressed claims made by climate change skeptics. What follows is the second part of the interview in which Brenda discusses current thoughts about climate change. The third and last part of the interview will be a separate post. It will focus on what individuals can do to help address this enormous and intensifying problem. Each post has been lightly edited for length and clarity.

As with the last post, this one includes lots of links to supporting background for those of you who want to learn even more!

Before getting started, here is some background on Brenda Ekwurzel. (This paragraph was also included in the post of the first part of the interview.) Brenda’s path to climate science started at Columbia University when, as a graduate student, she took a paleoclimate class.  At that time Brenda had the opportunity to go to the North Pole on an ice breaker. There, the experience of observing the evidence of rapid climate change firsthand, inspired her to focus on this area of science. She did post-doctoral work at Lawrence Livermore National Laboratory for two years. Later, as a member of the faculty at the University of Arizona, Brenda’s work included research with students on the changing precipitation patterns in the semiarid Southwest and how that is affecting groundwater supplies, mountain snowpack, and wildfires. Brenda has testified before Congress about climate change and has been widely quoted in the press and appeared on a variety of newsy shows including ABC News, CBS News and Good Morning America, among others. And because she is an equal opportunity expert she appeared on O’Reilly for the conservatives and The Colbert Report for the liberals.

Here is part two of the interview:

The Inspired Rationalist: Having addressed a lot of the points that climate skeptics make it would be helpful to summarize how scientists think about climate change today.

I’m specifically curious about the impact during the life of current millennials. I’m 60, my kids range from 25 to 31. I know we are already seeing profound changes but I’m not going to be around when the worst of this all plays out. My kids are going to be around as this all intensifies and certainly their kids. And so, I think focusing around that time frame is important to bring home the impact to the people we care deeply about – besides of course humanity in general.

Brenda Ekwurzel: We are all being affected right now by climate change and scientists have been warning us for several decades about this. Anyone who has lived or repeatedly visited a place for over thirty years has noticed the winter temperatures are not as cold as they used to be, wildfire season is more active in many western US mountains, summer air conditioning is needed in places that did not used to require it, when it rains it is more likely to be a drenching downpour and record-breaking weather events are making headlines. Hurricane Harvey is a recent example.

According to NOAA (National Oceanic and Atmospheric Administration), Hurricane Harvey dropped 60 inches of rain in Nederland Texas, breaking the 1950-2017 record for state maximum precipitation from tropical cyclones and their remnants. Renowned hurricane scientist, Kerry Emanuel, just published a study about the significance of the enormous average accumulated rainfall over Houston (840 mm or 33 inches). Assuming the precipitation area of individual hurricanes remains similar, he found that a 500 mm (19.7 inches) hurricane event was a once in a 100-year event back in 1981-2000.  This becomes a once in 16-year event by 2017 and a once in 5.5-year occurrence by the end of this century if emissions are unabated.  Scientists are repeating this analysis with other major extreme events.

So, climate change is here already and making a difference in our respective lives. Those of us who live in the US experience direct and indirect consequences, including taxpayers who repeatedly replenish the depleted U.S. disaster relief funds. Climate change will make even more of a difference as today’s children become adults and when their children are adults.  However, if the world achieves the Paris Climate Agreement we could have more options to adapt to a level of climate change that is around a degree Celsius added to the global average temperature change we experienced so far.  That would be a far cry from the unabated emissions world, with, for example, Hurricane Harvey precipitation over parts of Texas having a chance of occurring every 5.5 years.

It’s clear that our society has ignored the scientists for long enough and we haven’t built up resilient infrastructure and systems. In many parts of the U.S. and its territories insufficient resilience exists in sectors such as electricity, flood control, healthcare and supply chains during and following extreme events.  Building in more time for developing a successful suite of “adaptation” solutions for climate change can be achieved through substantial emissions reductions.

Besides, there is really, really scary stuff around the corner that is worth fighting to avoid, such as thresholds with the West Antarctic Ice Sheet that could be crossed in this century unleashing massive sea level rise. The good news is this threshold could also be avoided for a few centuries if the world achieves the Paris climate agreement.

An analogy is you walk out on the street and you suddenly see a car is going to hit you. Experts have been telling you that that car will come. The question is will it hit you at five miles an hour or 60 miles an hour? At five miles an hour the doctors might be able to patch you up and you’ll get on your way. The oncoming car speed is largely in our hands.  Collectively each of us, our communities, states, and the world’s citizens determine the future emissions.

IR: Can you explain the difference between five miles an hour and 60 miles an hour?

BE: Five miles an hour is the Paris climate agreement. There’s still going to be pain. There’s still going to be investment in the resources to patch you up, and make sure you’re resilient, and you’re in the best shape possible.  60 miles an hour is unabated emissions with dire consequences.

IR: Can you give some specific examples? You already mentioned that we’re already being impacted. Can you mention 2 or 3 things that we would be likely to see that would drive home an understanding where we would be in 50 years if we meet the Paris objectives?

BE: The Paris Climate Agreement means that we can keep pace with the change and adapt in many cases successfully.  You’re going to have some communities deciding to invest in ways to stop the flooding along the coastlines and rivers.  With unabated emissions, places that tend to flood at high tide today could be chronically inundated in 50 years and not practical to use for current activities.

IR: Miami is an obvious example.

BE: There are lots of communities up and down the coasts of the US on the frontlines of this choice. The Union of Concerned Scientists just issued a report identifying the communities facing chronic inundation under different cases. In a high emissions case the seas could rise 6.6 feet above 1992 levels by the end of the century.  A Paris Climate Agreement case, is around 1.6 feet of sea level rise by 2100 under the 1.5 to 2 degrees Celsius global average temperature increase above pre-industrial levels.  This analysis found that by 2060 around 180 coastal communities risk chronic inundation with the Paris Agreement.  By 2060 the number of communities doubles under the high emissions case.

IR: What would six feet mean, practically speaking?

BE: The high emissions case of over 6.6 feet means chronic inundation for communities that were not chronically inundated under the Paris Agreement low emissions case by 2100.  (The following table is from the Rising Seas Hits Home report data table for California:)

IR: There are a lot of people that live in coastal areas that are at sea level or close to sea level that are probably within that six-foot range. I would guess a few hundred million people globally that would be directly affected.

BE:   Including many in the U.S; over 13 million people risk inundation with around 6 feet of sea level rise.  Including many people serving at military sites.  The Navy is doing a lot of advanced work to protect their facilities from rising seas. They know this is an issue. Of course, climate change increases risks beyond sea level rise.

IR: The impact on species?

BE: Many impacts on species with a future intertwined with the human species emissions choices.  For example, the Rocky Mountains may not look the same. Under high emissions there would be different trees, different species, especially in the southern portion of the range. Less forest, more grasslands, less snowpack, etc.   Tree species such as the quaking aspens have already declined in the Rocky Mountains.  Habitat suitable for Lodgepole pine could drop 90 percent by 2060.

IR: That gets into the food chain and what the impact could be.

BE: There would be different places where you can grow certain crops as the plant hardiness zones shift to higher latitudes in the continental U.S.  Growers have planning decisions for the long-cultivation crops such as tree nuts and grapevines.  Almonds typically require 3 years of cultivation before economic yields. Those risks are challenging. Adaptation changes likely mean different types of foods would be grown in different regions of the world.

And other species are going to face local extinction or global extinction.  There is recent concern over the massive coral bleaching along the Australian Great Barrier Reef from unprecedented high ocean temperatures these past couple of summer seasons.

The biggest looming issue for corals is further overloading the atmosphere with carbon dioxide and acidifying the oceans. The risk is that the ocean becomes so acidic that aragonite undersaturation occurs, crossing a threshold that triggers dissolving aragonite shells or corals. One reason this is important is that colorful organisms live on the coral structure forming a core factor needed for fisheries to thrive.

IR: How soon could this happen?

BE: Under high emission scenarios we could make aragonite undersaturation occur within this century. It is already being experienced in the cold and polar regions.  The question is when this would occur in the tropical regions.

IR: Is it hard for scientists to talk about the catastrophic risk climate change presents? Because, it can come off as alarmist and people can react to that and just dismiss it.

BE: I’m a person too and I don’t want these outcomes. But I know they’re very real and I know they’re very possible. We also know that if we talk about the risks, it can cause people to shut down and do nothing, which is exactly the opposite of what might be prudent. Ironically, scientists are always publishing papers on the high emission scenario because it’s the easier signal to see than keeping it to two degrees, which is still a lot of climate change. We’re at nearly a degree right now so that’s a whole other degree of change and its happening much faster.

IR: It seems to me that one of the big uncertainties is the amount of disruption that will be caused. How will the human reaction to that play out? You mentioned not knowing how we will do in weaning ourselves quickly off fossil fuels (this was discussed in Part 1 of the interview). That’s a critical uncertainty. Whatever way this plays out, there’s going to be disruptions and how humanity responds to those disruptions is a huge unknown in terms of the impact on people’s lives.

BE: Policymakers tend to respond to the crisis of the moment. By the time enough people see the crisis of climate change it’s too late because we would have unleashed thresholds that are irreversible and really hard and costly for society to deal with. We have to be better at talking about those risks even though they are hard for us to talk about. Some might choose to hazard those risks and most will urgently want to avoid them.

There are likely to be surprises. I think it would get real complicated real fast and we’ve trained our science based on what’s happened over historical time periods and what’s happened in the past climate.  However, the pace of change is often unprecedented, and therefore, uncharted territory.

So, we’re a product of what we know. The past is not a guide to the future, exactly, because it’s going to be a whole new world if we dramatically overshoot the Paris climate agreement target.  The first round of nationally determined contributions are the initial goals set forth by countries.  There is a process to keep revisiting and adjusting these national determined contributions to reflect technological advances, societal changes, etc.