Our readers know that we consider climate change the most critical environmental issue of our time. We also believe that the native plant ideology is antithetical to our concern about climate change for two reasons:
- The changing climate requires that plants and animals move in order to survive. Therefore, the demand that historical ranges of native plants and animals be restored and maintained is both unrealistic and harmful. It is unrealistic because the environment has changed in the past 250 years since the arrival of Europeans on the West Coast and it will continue to change. Therefore, we cannot assume that the native plants that existed here in 1769 are still capable of surviving here. It is harmful because animals can and do move as the climate changes. Therefore, eradicating the plants they need for survival is harmful to them.
- The eradication of non-native plants and trees is exacerbating climate change by releasing their stored carbon into the atmosphere, thereby contributing to the greenhouse gases that cause climate change. When prescribed burns are used to eradicate non-native plants or prevent natural succession the release of carbon into the atmosphere by the plants that are burned is immediate. When large, mature trees are destroyed, the carbon they have stored as they grew is released into the atmosphere as the wood decays. Furthermore, their ability to store carbon in the future is lost to us going forward. Since carbon storage is directly proportional to biomass, whatever we plant in their place is incapable of storing as much carbon as the mature trees.
There is an important caveat that we must add to our first bullet point. Changing location is not the only mechanism that can ensure species survival in a changing climate. Many species are probably “pre-adapted” to the changed climate. That is, they may be capable of surviving changes in the climate. Secondly, species can adapt and/or evolve in response to changes in the environment, which is another mechanism that facilitates species survival. We invite our readers to visit our post about the rapid evolution of finches in the Galopagos Islands in response to extreme weather conditions that caused selection events.
Today we will inform our readers of the scientific record regarding the need for plants and animals to move as the climate changes. We will use the recently released fifth report of the Intergovernmental Panel on Climate Change as our source.
Intergovernmental Panel on Climate Change
First we will establish the credibility of the Intergovernmental Panel on Climate Change (IPCC). The IPCC was formed in 1988 by the United Nations. It is composed of thousands of scientists from all over the world, representing the 190 member nations of the UN. The IPCC does not conduct original research. Rather it compiles thousands of peer-reviewed scientific studies into reports that represent a consensus viewpoint of the global scientific community. Typically, scientists from 120 countries participate in marathon sessions in which consensus must be reached before reports can be published. The IPCC has published 5 reports since 1988, the most recent earlier in 2014.
How the climate has changed and how it will continue to change
The IPCC compiled several different sources of data to report how the climate has changed from 1900 to the present. Then they modeled the multitude of variables that influence climate to predict different trajectories for the climate going forward to 2100. The many variables that influence climate interact in complex ways that are not entirely predictable. There is therefore some uncertainty in those predictions, as there is in any prediction of the future. Therefore, future temperature is depicted by the following graph as “bands” of probability. The bands become wider as the graph depicts further into the future, as we would expect; that is, the distant future is less predictable than the near future.
Here’s what we learn from this graph:
- The graph reports that the average global temperature has increased by 1° Celsius (1.8° Fahrenheit) from 1900 to the present. Graphs depicting the more distant past indicate that the climate began to warm around the time of the industrial revolution, about 1850. Therefore the total increase in temperature is greater than that depicted by this graph. However, the rate of increase has accelerated greatly in the past 50 years.
- The upper range of projected temperature increases on the graph is labeled RCP8.5 (Representative Concentration Pathway 8.5). That pathway is based on the assumption that present levels of greenhouse gas emissions will continue to increase at the same rate as they have in the recent past. The mean prediction of that pathway is a global temperature increase from the present to the end of the century of 3.7° Celsius (4.6° Fahrenheit).
- The lower range of the projected temperature increases on the graph is labeled RCP2.6 (Representative Concentration Pathway 2.6). The mean prediction of that pathway is a temperature increase to the end of the century of 1° Celsius (1.8° Fahrenheit). That pathway is based on the assumption that greenhouse gas emissions are radically reduced, beginning immediately, as represented by the following graph from The Guardian. This graph also depicts two intermediate emission scenarios between the present trajectory(RCP 8.5) and the maximum predicted reductions in emissions (RCP 2.6)
Movements needed for survival in a changing climate
The world has done little to reduce greenhouse gas emissions and America has done even less. According to a recent Gallup Poll, only 39% of Americans are “concerned believers” in climate change. Another 36% of Americans believe the climate is changing, but don’t believe it will affect them. Twenty-five percent (25%) of Americans do not believe the climate is changing. Therefore, for the time being, it seems extremely unlikely that our polarized politics in America will be capable of responding effectively to the grim reality of climate change. Within that context, we inform you of the final graph from the IPCC report about the need for plants and animals to move from their present ranges in response to climate change and their variable ability to do so.
On the vertical axis, the graph depicts the ability of plants and animals to move, measured in kilometers per decade. The horizontal lines depict the need of plants and animals to move in response to various scenarios of climate change as we described earlier. The bars depict the ability of plants and animals to move and the height of each bar informs us of the variable ability of plants and animals to move. Trees are the least able to move, unless we have the wisdom to plant them outside their native ranges—at higher latitudes or elevations–where they are more likely to survive in the future.
For example, if we radically reduce greenhouse gas emissions immediately (RCP2.6), most species of trees and plants will be sustainable at their present latitudes and elevations. But if greenhouse gas emissions continue on their current trajectory (RCP8.5), most species of trees and plants will not be capable of moving far enough, fast enough to survive as the climate warms. Although trees and plants are capable of moving only very slowly, most animals are capable of moving more rapidly. Will they have the plants they need to survive in their new ranges?
Putting our heads in the sand
Surely there aren’t many native plant advocates in the San Francisco Bay Area who don’t believe in the reality of climate change. The Gallup Poll reports that most people who don’t believe in climate change are Republicans and in the San Francisco Bay Area Republicans are a small minority. And so we ask native plant advocates this question: How do you reconcile the reality of climate change with your demand that native plants be restored and maintained where they existed 250 years ago in a very different climate?