“Net-zero” Emissions

The Secretary of Environmental Affairs would be required to adopt a “2050 statewide greenhouse gas emissions limit of not more than net-zero emissions” under legislation that the Senate passed yesterday.  Both the House speaker and the Governor have also spoken favorably of the “net-zero” goal, so the requirement is likely to become law.

Why “net-zero”? Is it enough?  There is a difference between “zero” and “net-zero.”  Zero would imply that we never used fossil fuels for any purpose.  That does not seem a realistic goal to set for 2050. While electricity can substitute for fossil fuel power in most contexts, it seems likely that we may need to continue to use fossil fuel for backup power for critical functions like hospitals and emergency vehicles. 

“Net-zero” allows the Commonwealth to do a balanced accounting for carbon emissions, including things like forests that take carbon dioxide out of the atmosphere to offset our continuing limited fossil fuel use.  If the whole world could achieve “net-zero” then at least we would have stopped increasing the amount of carbon dioxide in the atmosphere. The International Panel on Climate Change has recommended this net-zero goal. They find that net zero by 2050 is likely necessary if we are to hold warming to 1.5 degrees centigrade.

In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050 (2045–2055 interquartile range).1

IPCC, Global warming of 1.5 Degrees Centigrade, Chapter Two Executive Summary

There are two ways to account for  atmospheric carbon dioxide. First, for state or national goal setting, we tend to focus on the tons of carbon dioxide that we are putting out annually.  So, we think in terms of annual reduction targets and long-term stretch goals for annual emissions like “net-zero” by 2050.

Second, since carbon dioxide remains in the atmosphere for thousands of years, we need to look at the cumulative amount that has been released and now remains in the global atmosphere, expressed as parts per million. The parts-per-million goal feeds in to the models that compute how much heat is trapped by the “greenhouse” effect.  The models work from the parts-per-million number and other factors to determine how much temperatures are likely to rise overall.

Because the parts-per-million level is cumulative of all the annual emissions, it matters a lot how fast we get to “net-zero.”  The faster we get there, the less total emissions and the lower the parts-per-million level. If world emissions remain high for several more decades then we will experience a lot of irreversible warming, even if we ultimately get to “net-zero.”

So far the world hasn’t made much progress in reducing annual emissions, much less the total stock of carbon dioxide in the atmosphere.  For all of our effort and conversation, it appears that 2019 was the highest emission year ever. Fundamentally, economic growth requires more energy use and the increase in energy use is outpacing our rate of conversion from fossil energy to other sources of energy. 

China accounts for a large share of both global economic growth and the growth in carbon dioxide emissions.  Other developing countries are also expanding emissions. We certainly cannot begrudge these countries their economic growth — they are entitled to enjoy the mobility and prosperity that we enjoy.

Global and China Emissions: 1960-2018 (globalcarbonatlas.org)

Given that the world is likely to fail to reduce emissions for some years, we will eventually need to achieve negative emissions and reverse the accumulation of carbon dioxide if we hope to limit global temperature rise.  Most of the modeled scenarios in which we are able to limit warming depend on as yet unknown methods for pulling carbon dioxide out of the atmosphere.

All analysed pathways limiting warming to 1.5°C with no or limited overshoot use [carbon dioxide removal] to some extent to neutralize emissions from sources for which no mitigation measures have been identified and, in most cases, also to achieve net negative emissions to return global warming to 1.5°C following a peak (high confidence). The longer the delay in reducing CO2 emissions towards zero, the larger the likelihood of exceeding 1.5°C, and the heavier the implied reliance on net negative emissions after mid-century to return warming to 1.5°C (high confidence).

IPCC, Global warming of 1.5 Degrees Centigrade, Chapter Two

We should see the “net-zero” goal for Massachusetts in this larger context.  “Net-zero” is not an endpoint. It is a waypoint on a path to a further goal of “net negative.”  Targeting “net-zero” by 2050 will not deliver us from the risk of climate change. But by pushing hard for our economy to be greener, we are supporting innovation in energy production, energy storage and energy conservation.

Supporting energy innovation is probably critical to our future.  Wholesale reductions in emissions have so far proven difficult for every nation, involving sacrifices that people are unwilling to make. The most significant reductions have come because natural gas has become a cheaper fuel source than coal.  Both coal and natural gas generate carbon dioxide, but coal generates more. (See for example, Massachusetts.) Our hope has to be that through continued innovation clean technology will become so cheap, reliable, and convenient that people want to switch to it voluntarily.

So, I’m glad that we are considering a more ambitious “net-zero” goal for the transformation of the Massachusetts economy and I am hopeful that in this legislative session we will enact the new goal and fully support it with strong monitoring and enforcement as contemplated in the Senate legislation.

For details on what else is in the package, please see this post.

Published by Will Brownsberger

Will Brownsberger is State Senator from the Second Suffolk and Middlesex District.

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48 Comments

  1. Wow! What a very informative article, thank you. I hope we are eventually able to achieve zero, but until that time I think net-zero is a very ambitious and achievable goal!??

  2. The science suggests that net-zero should help stabilize the climate. BUT…

    This is only if we take the timing of “offsets” into account. We cannot, for instance, cut down trees today, burn them, and then let the “carbon reduction” (offset) for replanting be credited all in the first year. The trees will regrow for several decades to come. That isn’t “net-zero” on the time scale that climate crisis requires.

    When considering carbon removals, please use their annual removal values (how much carbon did a new tree remove THIS year) to offset a given year’s emissions. Same for soil carbon, direct air capture, and other negative emission sources/technology.

    I support the ambition of the recent Senate bills, but please make sure that carbon accounting doesn’t make a joke of the well-intentioned ambition.

    1. This is an important point and thanks for raising it.

      It’s important how we classify what is “renewable” or “clean” to avoid cases like Palmer Renewable Energy’s proposed wood burning plant: https://www.masslive.com/news/2019/08/environmental-groups-accuse-state-of-deeply-flawed-review-of-biomass-changes-call-for-more-input.html
      (full disclosure: my asthmatic son lives near the proposed site of this “renewable” wood burning plant.) If you look more closely at Germany’s otherwise remarkable achievements (and possibly Vermont’s?) you see stuff like this too.

      Speaking of “clean” fuel, recent studies and articles call into question how clean natural gas is, whether it’s much cleaner than coal at all after considering the leaked gas and concerning yourself with the chance of passing dangerous thresholds on the 10 to 50 year time frame vs. 100 year. But for Massachusetts that doesn’t matter. Coal has been killed here and now natural gas must be the next target.

      And let’s target it right away since we all seem to assume electric cars will be the deus ex machina saving us from making more dramatic changes to cut down our transportation emissions. For electric cars to achieve anything much beyond their innate engine efficiency we need to get after NE ISO and the power suppliers, and we have to get offshore wind going.

      Remember that 30% of NE ISO’s power mix comes from nuclear plants that hardly seem likely to make it to 2050. So on top of the extra electricity for cars and shifting house heat to electric heat pumps we have to replace those nukes. This when wind and solar (smaller than wood and waste now in the “renewable” portfolio IIRC) presently form a very similar sized wedge in a pie graph to that of public transit miles traveled in the graph Senator Brownsberger has been including in presentations showing public transit miles traveled vs. auto miles traveled, the graph that has him convinced that we have to accept that we’ll continue to put cars first in our considerations.

  3. Will,

    At the same time, I was thinking of reaching out to get your opinion on this, your email hit my mailbox. Thanks for being proactive on this topic.

    The facts are clear but I really struggle with our ability to get to net-zero without huge technological advancements. A good example are incandescent to LED bulbs. My understanding is LED lights use less than 20-25% of the energy used in incandescent. Albeit not perfect yet, that drop is extraordinary and where we need to go with other carbon-related issues.
    The other thing I can’t get my head around is we talk about using electricity more. In fact, I think I read somewhere, some towns have even proposed to not allow gas, oil, or coal furnaces on new buildings. The problem is (and I am no expert here) that electric power is probably being created elsewhere by high carbon-emitting solutions. How does that help? It makes us feel good because the usage is “clean” but the source certainly is not, and while adding a higher cost to us as users.
    Again, I don’t have the answers but the investment to get to affordability by advancements in technology is dead on. I am glad you see that.
    BTW, the one technology I wish they would nail down is solar roof tiles. I am not a fan of today’s panels on rooftops but if they finally come up with solar roof tiles that look like asphalt shingles, at a reasonable cost, I would be all over it.

    Thanks for listening and best of luck.

    1. John — some towns, like Somerville, have the option of purchasing electricity from 100% renewable (wind, solar, hydro, presumably) so no fossil fuels are used to generate the power needed. Thus, zero carbon emissions. One pays a very slight increase in cost per kw for 100% renewable. One would hope that 100% renewable choices would actually cost LESS than using carbon-generating alternatives. Utilities need to get the pricing right to provide the right incentives. And yes, there are solar roof shingles, but cost is high. However, the price of them, combined with the cost of potentially needing a new roof, might look a bit more appealing when all things are considered.

      1. There’s also the option, where available, to join a shared solar arrangement like https://www.clearwaycommunitysolar.com, which, unlike Somerville’s program, can offer a slight reduction in your rate in exchange for a 20-year contract (transferrable, but you have to find the new customer). It strikes me that with some tweaking of the utility rate structure under the new legislation, programs like this could leverage market forces that would move us all very quickly (subject to limits on solar/renewable supply, of course) away from using electricity generated by oil and gas. That would leave us with the problematic technology and economics of converting gas and oil heating systems to electricity . . .

    2. It is possible — not easy, but possible — to replace carbon-burning electrical generators with solar/wind/hydro/tidal/… generators combined with storage mechanisms that store excess power when it’s generated and release it when nature doesn’t provide. (Some of these mechanisms are already in limited use; solar concentrators can heat salt deposits which later generate steam to drive turbines, pumps can use excess electricity to push water back above hydropower dams, etc.) Making new construction use electricity from the start looks cheaper than replacing carbon-fueled appliances later on, and could lower construction costs by not requiring dual supplies (since electricity is needed in all homes). Whether the grid can support this is a question I haven’t seen addressed — but the gas companies are still telling us we need more supply trunk lines, so maybe that money should go to the power grid instead.

    3. Everything that Charles Hitchcock said, and/but also, if we can be a little more flexible in other constraints — how our roofs look, for example — it will be far easier to get to net zero. Demanding that everything else stay exactly the same except for the greenhouse gasses is actually really hard, especially if we want to make progress sooner.

      To use an example from my childhood, in Florida, you need a lot less air conditioning if professional workers (managers, politicians) do not feel like a dark wool suit is part of their official uniform. It wasn’t always like that, light-colored seersucker and linen are darn useful in hot, humid weather. A/C used to be a luxury, and dress and housing accommodated that fact.

    4. You are spot on the central practical question: how carbon free we can make our electric supply sources and how fast we can do so? It’s hard to get good answers on this because so much of the expertise is within industry (fossil or renewable). The industry experts inevitably have a slant. But I recognize the question and I’m trying to get better information. For cool real time information on the fuel mix, get the ISO New England app on your phone!

  4. This is very helpful and exciting. And, 30 years to get to net zero is likely too slow? Do you see a way to be more ambitious? Thanks for your leadership on this important issue.

  5. This is truly great news. I can’t tell you how good this is as a citizen of this state to feel like we are moving in this direction.

    You are asking about the legacy carbon in the atmosphere already, and how to get that down. Are you aware of the concept of regenerating the carbon cycle and pulling carbon from the atmosphere and getting it back into our soils around the planet where it belongs? Once there it holds moisture (and lots of it), and supports the microbial life of the soil, which in turn holds some of the carbon there, and supports healthy crop growth with little or no chemical inputs.

    There is much happening around the world to make this happen, and I do wonder if you have tuned in to it.

    1. Macky Buck – that technology has been around for 370 million years. They’re called … trees. Let’s not recreate the wheel here.

  6. Wonderful news! I’m very grateful to live in a progressive state that actually is serious about reducing our carbon footprint.

  7. Not sure why you object to currently available solar roof tiles. I put them on my 120 yr old beautiful Victorian home more than a decade ago. They look great, reduce our carbon footprint and make us feel good because we are creating clean energy that we feed into the grid.

  8. Will, how is Massachusetts doing on it’s 2015 goal of 25% carbon reduction by 2020? Do more unrealistic goals make sense?

  9. If I could wave a wand I would have Massachusetts invest $1 billion/yr in free carbon capture, which is a technology that sucks CO2 out of the atmosphere and sequesters it, perhaps in the deep ocean. At $100/ton, $1 billion would capture 10 million tons the first year, 20 million the second (for a total of thirty), and so on. If I am reading the graphs of your text right we would be at zero total emission in ten years and thereafter would be running in reverse. A gift to the world.

    1. We pick up the tab while China reaps the benefits, in effect the state subsidizing China. They can keep on going with impunity while we pick up the mitigation costs.

      1. As I said, it would be a gift to the world.
        Appropriate though, considering how much CO2 we — however you want to define that term — have put into the atmosphere over the past hundred years. It seems only right for the people who put the pollutant out there should pay to have it picked up.

    2. Where do you get the costs from? The paper I found with costs in that range ( https://sequestration.mit.edu/pdf/David_and_Herzog.pdf, from MIT so I hope for less spin than an industry paper ) assumed capture at fossil-fuel power plants where CO2 is already concentrated. This is not the same as pulling it directly out of the air, and would thus still require electrifying all our home heat and transportation. (And, also, they assume 10% still escapes, which is much better than 100%, but not zero.)

      Sequestering in the ocean also seems iffy to me; that would still acidify the ocean as the CO2 spread through it, which would have all the bad effects on ocean chemistry (coral, etc) and also reduce the oceans’ ability to buffer CO2 from the atmosphere; in the very long run we would end up at exactly the same equilibrium and we’d doom our distant descendants (truly, we would, we would land them in worst-case warming, though that might be 1000 years away).

      Nonetheless, carbon capture right now in power plants, and sequestering in the deepest and most stable possible rock formations, sounds like a good short-term measure that could buy us time. We use plenty of electricity already and a lot of that is fossil-fueled.

      1. I’m all for carbon capture. I haven’t gone deep on it, but everything I hear says it is not ready for prime time at scale. Think of the train loads and pipelines full of carbon (oil, gas, coal) rumbling into power plants. Now try to imagine them running in reverse to bury the burned product (which is two or three times as heavy).

  10. Thank you for working to get our tiny state of Massachusetts to Net Zero. This is an important step, and Massachusetts should be a leader. We need this and carbon sequestration at the same time. We can’t wait for everything to be cheap and easy and voluntary, we don’t have time.

  11. I think you should start at the top of the Carbon Dioxide/Oxygen cycle and just fire Mother Nature. I feel strongly she has been over-worked and needs the time off. (Tongue In Cheek, just a bit).

  12. Yes, very nice feel good legislation that will cost us more dollars for our power but does nothing to solve the problem because unless you get China, India and a few other countries to accomplish the same goals it will mean nothing.

    1. I completely agree that we can’t get there alone and our reductions will be swamped by increases elsewhere. But making the effort here may advance technology that we can spread elsewhere — thats the reason to do it.

    1. It’s right to be suspicious of people advocating for poor people to cut their carbon footprint, but overall, I accept the scientific consensus that climate change is very dangerous especially for poor people. and we do have to find a way to get off fossil fuel.

  13. Will (and others), I want to thank you for a lot of good information and for the reference to the 19 page report on Massachusetts progress in meeting its goals, which I have saved onto my desktop to study when I’m more wide awake. At first reading, I’m quite impressed. Had no idea we had been such a leader…….AND I want to recommend to all a book by Alan Safran Foer called “We are the weather: Saving the planet begins at breakfast.” Foer believes we’ve stressed reduction in fossil fuels without sufficient attention to the huge carbon footprint that our food choices make. According to the author, fossil fuels account for 25% of harmful greenhouse gas emissions and agriculture 24%, primarily due to industrial animal farming. If all of us could move towards a plant based diet with minimal use of meat (particularly beef and lamb), as well as milk, cheese and eggs and shellfish, we could significantly reduce our carbon footprint.

  14. We need to talk. Have the conversation from a growth based economy about where and how to reach “mature sustainable size”. I am looking at especially transportation if we are encouraging and facilitating more 2019 emissions years being baked into the system with our underlying assumptions on transportation infrastructure development. Climate change is a facet of the economy, put the stopper into the tub before turning on the tap and the tub will fill to the right level.

  15. Good, strong position, Will.
    Brookline and Cambridge are moving ahead with local legislation to require new buildings to have “zero” on-site emissions (“fossil fuel fee”) right now. The new state-wide legislation is great, but we’ve got to keep pushing for more.

  16. Hi,
    Regarding China’s use of fossil fuel. China is grappling with climate change, not ignoring it. “While this latest turn in the US administration’s climate policy {Trump planning to leave the Paris Accord}might be disappointing for the global effort, China’s policy at this point has a standalone logic and an internal coherence that makes a change of direction highly unlikely. China plans to be the supplier of low-carbon goods to a carbon-constrained world: It already boasts the world’s biggest installed capacity of wind and solar power, and its climate policies are built in to its current five-year economic plan.” The Guardian, November 2016. If we think China should reduce their use, we can’t be hypocrites, which decreases our credibility. Rather we need to support their considerable efforts.

    1. You really believe that they are going to meet the emission goals they provided us, then you must also believe that they are going to STOP stealing our technology? I can only wish it were true!

  17. Will,
    Many thanks for your thoughtful post on a MA net-zero emissions goal. In the current vacuum of federal leadership on climate, ambitious state policies, informed by science, are essential. Massachusetts is well-positioned to be a climate and energy policy leader, through setting this net-zero target and through smart more specific policies to reduce emissions from energy and transportation.

    I just want to gently take issue with your statement that
    “The most significant reductions have come because natural gas has become a cheaper fuel source than coal. Both coal and natural gas generate carbon dioxide, but coal generates more.”
    Coal may generate more carbon dioxide, but expanding natural gas use increases emissions of methane – a very potent greenhouse gas – making natural gas no better than coal for the climate under most conditions. Herein MA and elsewhere, we face hard choices about our energy futures, but over-reliance on natural gas won’t get us anywhere near the net-zero greenhouse gas (not just carbon) emissions targets that we are poised to adopt.
    Thanks again for your thoughts and continued support for strong MA climate policies.

    Peter Frumhoff

    1. Of course, you are right, Peter. I completely agree that natural gas will not get us where we need to go. Many feel that it is helped us make the limited net reduction we have achieved, although a full accounting for lost methane might suggest we have not gotten as far we think we have.

      1. Will,
        If we know that expanded use of natural gas is exacerbating the climate problem will you support a state-wide ban on natural gas service in new construction? If we know that energy generated from the sun helps mitigate the damage from climate change will you support a requirement for solar panels in all new construction?

        1. Thanks, Roger.

          I like those ideas in principle, but I’m not sure we can really force them quite yet. For one thing, solar doesn’t work well on every roof. For another, until we have a greener grid, it’s sometimes better to burn gas for heat on site than to burn it for power and then transmit the power. I think a better approach is to price carbon and give people the incentives to make better choices. That’s what the bill does.

  18. What is the optimal level of CO2 in the atmosphere, and who determines what the optimal level of CO2 is?? Why is it just the western countries that have to achieve these UNREALISTIC goals??

  19. Thank you for your summary of the most critical crisis of our time. It’s truly chilling to know that models for a livable planet rely on discovered technologies. We must be aggressive at every scale.. our individual choices and our government policies. I support this legislation and meanwhile eating fewer and mostly local animal products.

  20. Hi Will,
    As usual you have immersed yourself in the science, the politics and the economics to produce an excellent position posting. Thanks for that.
    Here are a few points:
    1. The pursuit of economic growth and the perpetuation of our current economic system are the main factors that have limited the worldwide response to the climate emergency. Growth has been sold as necessary for our liberal democratic society and world order, but closely examined, really serves only a small minority of people. We need to rethink our goals.
    2. Let’s consider what our day to day might look like in 2050 as the world fails to reach even modest carbon drawdown goals. Temperatures in the 120’s, coastal properties lost to ever higher tides, tornadoes a regular occurrence in our state. If we truly want to enjoy our balmy springs and ski-able winters, we have to do better, sooner, deeper.
    3. We have to close the gap between what thoughtful people think should be done by governments and corporations to address the climate emergency, and what we will be willing to personally sacrifice. There is no magic here. Without this, a devastating global future will be forced upon us, with repercussions falling hardest on those least able to deal with it. That will be our legacy.
    4. 2050 is a nice goal for net zero. And yes, some fossil fuels may still be necessary if we can’t get auto, truck and aircraft makers to develop new technologies quickly. But the use of fossil fuels can only be tolerated in the context of an even more significant reduction of CO2 levels.
    5. Why not legislate a stretch commitment to go net zero by 2028? We mobilized incredible resources to fight fascism in the 1940’s with very little time. Did we become weak and flabby in the intervening years? Is our technology less salient or our scientists less able now? If we weren’t worried about stock market levels, shareholder value and CEO salaries, we might already be there.

    I realize that politics is a game of compromise, but climate is a different animal that requires bold leadership to tame. I think you and we can do this.

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