CICERO Research Archive (CICERO Senter for klimaforskning)
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Climate-driven chemistry and aerosol feedbacks in CMIP6 Earth system models
Get PDFFeedbacks play a fundamental role in determining the magnitude of the response of the climate system to external forcing, such as from anthropogenic emissions. The latest generation of Earth system models includes aerosol and chemistry components that interact with each other and with the biosphere. These interactions introduce a complex web of feedbacks that is important to understand and quantify. This paper addresses multiple pathways for aerosol and chemical feedbacks in Earth system models. These focus on changes in natural emissions (dust, sea salt, dimethyl sulfide, biogenic volatile organic compounds (BVOCs) and lightning) and changes in reaction rates for methane and ozone chemistry. The feedback terms are then given by the sensitivity of a pathway to climate change multiplied by the radiative effect of the change. We find that the overall climate feedback through chemistry and aerosols is negative in the sixth Coupled Model Intercomparison Project (CMIP6) Earth system models due to increased negative forcing from aerosols in a climate with warmer surface temperatures following a quadrupling of CO2 concentrations. This is principally due to increased emissions of sea salt and BVOCs which are sensitive to climate change and cause strong negative radiative forcings. Increased chemical loss of ozone and methane also contributes to a negative feedback. However, overall methane lifetime is expected to increase in a warmer climate due to increased BVOCs. Increased emissions of methane from wetlands would also offset some of the negative feedbacks. The CMIP6 experimental design did not allow the methane lifetime or methane emission changes to affect climate, so we found a robust negative contribution from interactive aerosols and chemistry to climate sensitivity in CMIP6 Earth system models.publishedVersio
Kristiansands klimagassutslipp mot 2030: Referansebane og tiltakspakker
Get PDFCICERO Senter for Klimaforskning og Transportøkonomisk institutt (TØI) har utarbeidet en beregningsmodell og et sett med framskrivinger for klimagassutslipp i Kristiansand kommune fram til 2030. Framskrivingene omfatter en referansebane og anslått effekt av en rekke ulike utslippsreduserende tiltak. Framskrivingene kan brukes til å illustrere hvordan klimagassutslippene i Kristiansand kan tenkes å utvikle seg under ulike antakelser, og hvilken type innsats som kreves for å oppnå Kristiansand kommunes mål om 80 prosent nedgang i klimagassutslippene fra 2015 til 2030.
Referansebanen anslår hvordan utslippene kan utvikle seg uten nye utslippsreduserende tiltak eller virkemidler utover nåværende vedtatt politikk, og danner et grunnlag å måle effekten av tiltak opp mot. Tiltaksberegningene er satt sammen i fire ulike tiltakspakker, som både er tematisk gruppert og samtidig gjenspeiler både økende effekt og stigende ambisjonsnivå
I referansebanen går utslippene ned med 13 prosent fra 2015 til 2030. Nedgangen fra 2015 til og med 2020 skyldes i hovedsakelig økende nasjonalt omsetningskrav for biodrivstoffandel i drivstoff til veitrafikk samt voksende andel elbiler i veitrafikken og et lite bidrag fra utfasing av fossil olje til oppvarming i tråd med nasjonalt forbud mot mineralolje til permanent byggvarme. Fra 2020 til 2030 skyldes nedgangen hovedsakelig elektrifisering av personbiler og varebiler, en moderat nedgang i mengde forbrent avfall samt metanutslipp fra gamle avfallsdeponier, og en beskjeden nedgang i utslipp fra sjøfart i tråd med utvidelser av landstrømbruken og effektivisering og noe økende bruk av lavutslippsløsninger for nye skip eller skip som oppgraderes i løpet av perioden. Utslipp fra tunge kjøretøy og dieseldrevne motorredskaper vokser derimot over perioden, og bidrar til å dempe utslippsreduksjonen noe.
Hvis alle tiltakene i tiltakspakkene gjennomføres, anslår vi en nedgang i samlede klimagassutslipp på 87 prosent fra 2015 til 2030, tilsvarende 83 prosent reduksjon i utslippene i 2030 i forhold til referansebanen. Tiltakene overoppfyller altså målet om 80 prosent reduksjon fra 2015 til 2030 noe. Halvparten av reduksjonen kommer imidlertid fra den relativt krevende tiltakspakke 4, hvor tiltak som nullutslippssoner for de fleste typer kjøretøy og nullutslipps- eller hybridframdriftsløsninger på alle nye og oppgraderte skip er sentrale tiltak. I de øvrige pakkene er karbonfangst på avfallsforbrenning det største enkelttiltaket, som også er å regne som et relativt kostbart tiltak.
Når man i tillegg tar høyde for usikkerhet i beregningene, er det klart at 80-prosentsmålet ikke gir rom for å la utfordrende tiltak ligge, og vil kreve stor innsatsvilje og en god dose politisk mot. Det er også viktig å huske på at selv om referansebanen gjenspeiler nåværende politikk, så gjennomfører heller ikke den seg nødvendigvis selv. Den må følges opp, og politikere og administrasjon må være klare til å innføre kompenserende tiltak hvis det viser seg at utslippene ikke går like mye ned som forventet eller hvis forutsetningene endrer seg. Eksempler på situasjoner som kan oppstå kan være at høyere strømpriser gjør landstrøm mindre attraktivt, eller et bortfall av nasjonale insentiver for kjøp av elbiler.
Tiltakene er en blanding av tiltak som kan utløses helt eller delvis av kommunale virkemidler, tiltak som er helt avhengige av vedtak og finansiering på statlig nivå, og tiltak som krever statlig innsats for å utløses helt, men hvor kommunen kan bidra vesentlig. For de aller fleste tiltakene har kommunen likevel en viktig rolle å spille som initiativtaker, koordinator, pådriver eller gjennomfører, selv når et tiltak er avhengig av ressurser eller vedtak på statlig nivå eller samarbeid med private aktører.publishedVersio
A review of trends and drivers of greenhouse gas emissions by sector from 1990 to 2018
Get PDFGlobal greenhouse gas (GHG) emissions can be traced to five economic sectors: energy, industry, buildings, transport and AFOLU (agriculture, forestry and other land uses). In this topical review, we synthesise the literature to explain recent trends in global and regional emissions in each of these sectors. To contextualise our review, we present estimates of GHG emissions trends by sector from 1990 to 2018, describing the major sources of emissions growth, stability and decline across ten global regions. Overall, the literature and data emphasise that progress towards reducing GHG emissions has been limited. The prominent global pattern is a continuation of underlying drivers with few signs of emerging limits to demand, nor of a deep shift towards the delivery of low and zero carbon services across sectors. We observe a moderate decarbonisation of energy systems in Europe and North America, driven by fuel switching and the increasing penetration of renewables. By contrast, in rapidly industrialising regions, fossil-based energy systems have continuously expanded, only very recently slowing down in their growth. Strong demand for materials, floor area, energy services and travel have driven emissions growth in the industry, buildings and transport sectors, particularly in Eastern Asia, Southern Asia and South-East Asia. An expansion of agriculture into carbon-dense tropical forest areas has driven recent increases in AFOLU emissions in Latin America, South-East Asia and Africa. Identifying, understanding, and tackling the most persistent and climate-damaging trends across sectors is a fundamental concern for research and policy as humanity treads deeper into the Anthropocene.publishedVersio
Responses of Arctic black carbon and surface temperature to multi-region emission reductions: A Hemispheric Transport of Air Pollution Phase 2 (HTAP2) ensemble modeling study
No full textBlack carbon (BC) emissions play an important role in regional climate change in the Arctic. It is necessary to pay attention to the impact of long-range transport from regions outside the Arctic as BC emissions from local sources in the Arctic were relatively small. The task force Hemispheric Transport of Air Pollution Phase 2 (HTAP2) set up a series of simulation scenarios to investigate the response of BC in a given region to different source regions. This study investigated the responses of Arctic BC concentrations and surface temperature to 20 % anthropogenic emission reductions from six regions in 2010 within the framework of HTAP2 based on ensemble modeling results. Emission reductions from East Asia (EAS) had the most (monthly contributions: 0.2–1.5 ng m−3) significant impact on the Arctic near-surface BC concentrations, while the monthly contributions from Europe (EUR), Middle East (MDE), North America (NAM), Russia–Belarus–Ukraine (RBU), and South Asia (SAS) were 0.2–1.0, 0.001–0.01, 0.1–0.3, 0.1–0.7, and 0.0–0.2 ng m−3, respectively. The responses of the vertical profiles of the Arctic BC to the six regions were found to be different due to multiple transport pathways. Emission reductions from NAM, RBU, EUR, and EAS mainly influenced the BC concentrations in the low troposphere of the Arctic, while most of the BC in the upper troposphere of the Arctic derived from SAS. The response of the Arctic BC to emission reductions in six source regions became less significant with the increase in the latitude. The benefit of BC emission reductions in terms of slowing down surface warming in the Arctic was evaluated by using absolute regional temperature change potential (ARTP). Compared to the response of global temperature to BC emission reductions, the response of Arctic temperature was substantially more sensitive, highlighting the need for curbing global BC emissions.publishedVersio
Entering, enduring and exiting: the durability of shared mobility arrangements and habits
Get PDFCar sharing could support a transition away from private vehicle ownership and use. Attempts to understand participation in car sharing have primarily focused on minor and major disruptions which catalyse change in practices. This paper examines how processes of entering, continuing or exiting car sharing systems unfold in Norway, the Netherlands, Sweden and the UK. Car sharing is conceptualised as an arrangement of elements assembled, adjusted and supported by events, practices and habits. Drawing on biographically-oriented household interviews, we build on and extend existing understandings of change and stability in car sharing in four ways. First, by focusing on households rather than individual users, the paper complements recent attempts to understand the decoupling of family and private-car-based mobility. Second, under-examined processes of exiting, alongside entry and continuation are considered. Third, it highlights the importance of recognising more imperceptible, gradual and continuous changes which might not necessarily coincide with a disruptive event. Fourth, habits of shared car arrangements are demonstrated to be fragile and not as deeply ingrained as those associated with ownership. Existing household practices and habits thus raise further questions about the potential for shared mobility services to disrupt the primacy of the car.publishedVersio
Metodikk for framstilling av klimaeffekt på kort og lang sikt
Get PDFCICERO Senter for klimaforskning har på oppdrag fra Miljødirektoratet utviklet og illustrert metodikk for framstilling av klimaeffekt på kort og lang sikt. Vi har vurdert klimaeffekt på to forskjellige måter, med vektfaktorer og med en veldig enkel klimamodell for å estimere temperaturbaner av utslippsbaner og utslippstiltak. Analysen bygger på tidligere arbeid CICERO har gjort for Miljødirektoratet. Mandatet CICERO fikk var analysearbeid på disse fire temaene: 1) Vurdering av behovet for å oppdatere GTP(10)-faktoren Miljødirektoratet i dag benytter. 2) Beregne norske utslipp med GTP(10), AGTP, GWP* og eventuelt andre vektfaktorer for ulike tidshorisonter. 3) Metodikk for framstilling av klimaeffekt på kort og lang sikt av ulike utslipp/utslippsreduksjoner i samme figur. 4) Metodikk for kostnadsberegninger.publishedVersio
Reduced Complexity Model Intercomparison Project Phase 2: Synthesizing Earth System Knowledge for Probabilistic Climate Projections
Get PDFOver the last decades, climate science has evolved rapidly across multiple expert domains. Our best tools to capture state-of-the-art knowledge in an internally self-consistent modeling framework are the increasingly complex fully coupled Earth System Models (ESMs). However, computational limitations and the structural rigidity of ESMs mean that the full range of uncertainties across multiple domains are difficult to capture with ESMs alone. The tools of choice are instead more computationally efficient reduced complexity models (RCMs), which are structurally flexible and can span the response dynamics across a range of domain-specific models and ESM experiments. Here we present Phase 2 of the Reduced Complexity Model Intercomparison Project (RCMIP Phase 2), the first comprehensive intercomparison of RCMs that are probabilistically calibrated with key benchmark ranges from specialized research communities. Unsurprisingly, but crucially, we find that models which have been constrained to reflect the key benchmarks better reflect the key benchmarks. Under the low-emissions SSP1-1.9 scenario, across the RCMs, median peak warming projections range from 1.3 to 1.7°C (relative to 1850–1900, using an observationally based historical warming estimate of 0.8°C between 1850–1900 and 1995–2014). Further developing methodologies to constrain these projection uncertainties seems paramount given the international community's goal to contain warming to below 1.5°C above preindustrial in the long-term. Our findings suggest that users of RCMs should carefully evaluate their RCM, specifically its skill against key benchmarks and consider the need to include projections benchmarks either from ESM results or other assessments to reduce divergence in future projections.publishedVersio
Hydrogen for shipping – Opportunities for Norway
Get PDFPhysical and economic properties of hydrogen mean that its potential as shipping fuel with current technologies is limited to some shipping segments, since alternative fuels are better suited for other applications. An additional challenge for hydrogen is the large investments needed in infrastructure for production, transport, and bunker, as well as improved engine systems for ships. The most promising potential for hydrogen is for short to medium shipping distances, where the capacity of batteries is insufficient, whereas natural gas and biofuels could be more competitive for longer distance operations due to higher energy density by volume.
Due to energy losses at each step along the hydrogen chain (from production, through processing, transportation and using hydrogen) as compared to using natural gas or electricity/batteries directly for running ships, hydrogen will be relatively more competitive than alternative fuels when:
a) Batteries have insufficient power storage capacity, and with infrequent possibilities to re-charge;
b) A sufficient tax on CO2 emissions makes the value of capturing CO2 from blue hydrogen production high enough to cover the CCS cost. With a high cost on CO2 emissions, natural gas (LPG or LNG) for shipping becomes less competitive;
c) Biofuels (HVO or LBG) are less competitive due to higher cost or technical challenges for a specific ship application; or
d) Using hydrogen production as a battery to store surplus production of renewable power is the best value, due to grid limitations, etc. Due to multiple hydro reservoirs in Norway such storage flexibility is of less importance for Norway than e. g. Germany.
Hydrogen is currently not competitive with traditional maritime fuels and likely also not competitive with some of the alternative fuels for shipping. This means that there is need for stronger incentives through a supportive policy-economic framework, e. g. through public funding of infrastructure, public procurement, or supportive funds. There are good opportunities for Norway-EU collaboration on improving green hydrogen technologies, not the least on hydrogen-fueled shipping. Hydrogen-based shipping means opportunities for a new and internationally competitive industry in Norway given our high competence in marine-related technologies, in particular designing and building advanced ships.publishedVersio
Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison
Get PDFRecent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns. The output of this process is a scenario framework exploring where the region is headed rather than how to achieve its goals, extrapolating its current policy efforts into the future. We find that Europe is currently on track to overperforming its pre-2020 40% target yet far from its newest ambition of 55% emissions cuts by 2030, as well as looking at a 1.0–2.35 GtCO2 emissions range in 2050. Aside from the importance of transport electrification, deployment levels of carbon capture and storage are found intertwined with deeper emissions cuts and with hydrogen diffusion, with most hydrogen produced post-2040 being blue. Finally, the multi-model exercise has highlighted benefits from deeper decarbonisation in terms of energy security and jobs, and moderate to high renewables-dominated investment needs.publishedVersio