3.2 What kind of climate policy fosters sustainable growth?

present economic activity, how warming will impact other parts of the biosphere or at what horizon climate change will exert its impact. Thus, under the numerous factors of uncer

tainty, it is also rather difficult to estimate whether the result of environmental regulation will be slower growth or green reforms are able to support positive growth even upon stopping pollution.

3.2.1 THE NORDHAUS APPROACH

Initially, Nordhaus (1975, 1977) also examined the growth effect of innovation and technological progress. He believed that the exhaustion of resources did not restrain long-term

growth, since scarcity enforces more efficient production

and the use of alternative, renewable resources. Having examined the carbon dioxide cycle and the economic effect of limiting emissions, Nordhaus turned to the increasingly more complex presentation of the geophysical relations. Thus, he built a neoclassical Ramsey model extended by geophysical relations, the DICE model (Dynamic Integrated

Climate–Economy; Nordhaus, 1992b) that describes the

economic effects of climate change, supplementing it with material flow and settlement equations. The model equations also include equations capturing the emissions and concentration of pollutants, and the effect of that on climate, as well as those describing the harmful effect of the climate pollution that curbs economic growth. Nordhaus

includes agricultural and health effects, as well as the effects on recreation services in the economic effects. The effects, time profile and economic consequences of climate change are most often captured in public policy analysis by Integrated Assessment Models, developed on

the basis of Nordhaus’ DICE model. One of the most important elements of these analyses is estimation of the effects of climate change, one indicator of which is the social cost of carbon 14 emitted during consumption or production, returned by the individual estimates. rid and Kiev or San Francisco and Chicago.

The growth models integrating the entire social and economic environment determine a pollution emission path, from which the atmospheric concentration of particles is calculated, yielding the future temperature, precipitation and sea level. Based on the damage function derived from the environmental results, the degree of economic damage and the expected growth dynamics can be calculated both at regional and global levels. The social cost of carbon deter

mines the optimal carbon tax path, based on which environmental policy can encourage the internalisation of

the costs of pollutant emissions. Thus, the government not only manages CO 2 emissions to limit global warming, it also fosters innovations implemented in cleaner technologies.

Based on the theories of the 1990s, although environmental pollution is harmful, the emission of greenhouse gases has no long-term effect on the sustainability of growth. According to the calculations of Nordhaus (1991, 1992a, 2008), although economic growth entails CO 2 emissions, warming of 3 degrees Celsius would only reduce the gross domestic product of the United States by one quarter, or a maximum of 1 percentage point. He estimated the damages related to the global economy, calculated at 2018 prices, to be roughly USD 80 trillion, hardly 1 percent of global GDP, and thus in his opinion warming only hinders future economic growth in the developed industrial countries to a small degree. Based on the results of the DICE models, he estimates the present value of the cost of emitting one tonne of carbon hardly at USD 21; thus, he proposes the introduction of only a moderate carbon tax to resolve the externalities. In a later analysis, he revises the former results, but still estimates the social cost of carbon only in the amount of USD 31 (Nordhaus, 2017). Thus, the Nordhaus approach acknowledges the negative impact of climate change (although it does not deem the degree thereof to be major), and he argues for growth that is

sustainable even without strong environmental protection.

However, the optimistic approach has been criticised in recent decades.

Among other things, critique has been levelled in relation to underestimation of the importance of the future, underdevelopment of the specification of the damage function, underestimation of the likelihood of

14  The social cost of carbon is the discounted present value of costs caused by one additional tonne of emitted carbon dioxide, which increases in time, since due to the rising level of greenhouse gases in the atmosphere each additional emission generates increasing damages. To illustrate this: the degree of one tonne of emitted carbon dioxide corresponds to the volume of pollutants emitted by a car on the route of roughly 3,500 kilometres between Madcatastrophes, and the extent of the damage it causes.

3.2.2 THE GREEN GROWTH SCHOOL

In 2006, HM Treasury (the Ministry of Finance of the United Kingdom) issued the report by Nicholas Stern, assessing

Climate Change estimated global economic losses at roughly

the analyses of the previous decades and discussing the

policy intervention even under high costs. Although the

impacts of global warming, which – in relation to climate change – outlined a problem that fundamentally differs from the findings of Nordhaus and of the early integrated models (Stern, 2006). According to the analysis of the modified PAGE model, applied by the Stern team, the natural and

economic damages may be substantially larger than previously estimated and also irreversible.

According to their analysis, if the present trends continue, as a result of the general costs and risks of climate change, from now on the level of global GDP will be by at least 5 percent lower annually, while if the risks and effects of the disasters there is a harmonised international taxation policy, a carbon

are taken into consideration more broadly, damages may be

as high as 20 percent of global GDP (Chart 3‑2).

According to Stern, emissions of greenhouse gases should be reduced by roughly 3 percent annually to avoid that the global temperature rises by more than 2 degrees Celsius, while the

social cost of carbon may exceed USD 200, i.e. several times

higher than the USD 20-30 derived from the DICE models. Since the benefits of strong and early interventions exceed the expected future costs of delay, according to the recom

mendation of the report fast and firm climate policy measures must be taken to reduce emissions of greenhouse gases and a global carbon tax should be introduced to make growth greener and achieve long-term sustainability.

Chart 3-2: Impact of climate change on global GDP based on the integrated assessment models and the Stern report

Percent GDP

5 0 –5 –10 –15 –20 –25 Previous studies Stern Review

Es�mates of the damage costs of climate change

In relation to the cost of carbon, the most radical estimate is provided by Ackerman and Stanton (2012), who believe that by 2050 the social cost of carbon may rise to some USD 1,500. At the macroeconomic level – similarly to Stern, and contrary to the optimistic estimate of the DICE models – in 2018 the report of the UN’s Intergovernmental Panel on USD 70 trillion, i.e. almost 10 percent of global GDP, even with a lower warming of only 2 degrees Celsius (IPCC, 2018).

At the same time, the success of the environmental policy implemented for green growth does not immediately

result in higher economic growth. In order to eliminate pollution, the whole society benefit of the interventions should exceed the cost of public policy. By supporting green innovation activities later on a technology may become available which makes it worthwhile to implement the public growth effects of the intervention are realised only later, after a transition period, public policy fostered sustainable growth over the entire horizon.

One distinct element of the green growth policy is that a

global solution is required in the field of emissions cuts. If Source: own compilation.

tax of the same rate is imposed on emissions in all countries. The disadvantage of local policies is that economic activity is mobile, and thus in the absence of coordination it can easily move between countries, thereby undermining the efficiency of the environmental policy.

In relation to the severity of climate change and the strictness of the environmental policy, the fundamentally different

results estimated by Nordhaus (1991, 2017), Stern (2006) and the followers of their school are attributable to several reasons.

Since climate change takes place over the long run, over the course of centuries, assessment of the future bears particular importance (Chart 3‑3). In the early DICE models, the value of the discount factor quantifying the importance of future is too high, i.e. it undervalues the importance of future, as a result of which these models significantly underestimate the effects of climate change (Stern, 2013).

In the integrated models, economic growth is controlled by exogenous factors in the single-product aggregated growth models, which ignores the role of innovation and also of sustainable growth through green innovations (Stern, 2013).

Due to the obsolete specification of the damage function, and to the simultaneous function relation between the

inputs, the temperature and the condition of the environment have no impact on the subsequent periods and skip entire sectors (e.g. biosphere services, size of rainforests, etc.) in the analysis (Pindyck, 2017).

The early models

underestimate both the probability of

disasters and the damages caused by such, and only attach low probability to the risks: they ignore the degree of consequential damages caused by disasters, the breaks caused in the social and environmental capital, the destruction of physical capital, mass migration and war conflicts (Weitzman, 2012; Pindyck, 2013). Including the number of extreme hot days in the damage function alone doubles the estimated value of the social cost of carbon (Moore et al., 2017).

It is the shortcoming of the integrated models that the

changes caused by climate change should be examined

both at the extensive and intensive margins: namely, due to the warmer weather, consumers install more air conditioners, agricultural companies deploy more irrigation systems (extensive margin) and also use them more often (intensive margin) (Auffhammer, 2018).

The geographic focus, i.e. whether the degree of damages is assessed at the national level, locally or globally, is an important difference. While Nordhaus focuses on the developed industrial countries in his analysis, Stern’s model presents – analysing the difference between the impacts on developed and underdeveloped economies – that due to their unilateral economic structure, dependence on agriculture, low level of technological development and weak adaptation capacity, climate change has a severe effect primarily on

underdeveloped economies, the spillover security risk of which, however, will also impact the developed world.

Chart 3-3: Social cost of carbon based on different estimates

300 266.50

250

200

150 147

100

50 24 37 42

0

Market Choice Act DICE-2016 model (based on Nordhaus)

Obama era es�ma�ons

Tol 2017 model es�ma�on Stern report 2006

Source: own compilation based on the Stern report (2006).

The analyses of the past decades related to the trio of climate change, sustainable growth and environmental policy, differ substantially from each other. However, most of the studies

agree that the mitigation of the external impacts calls for the introduction of a carbon tax. 3.2.3 RADICAL RESPONSE: DEGROWTH INSTEAD OF EMISSIONS?

In contrast to the green growth requirements, the latest and most radical response to the connection between sustainable growth and climate change is given by one of the schools of the post-growth economy, developed in the late 2000s, i.e. macro ecology. The school of de-growth,

formalised by the theory of Victor (2008) and Jackson (2009), fundamentally rejects the possibility of sustainable economic growth achievable by environmental policies.

The de-growth theory supports new ecological economic

models and approach, according to which, humanity needs to strengthen solidarity and cooperation, in addition to fundamentally changing our life and culture – changing consumer habits and reducing market competition.

The de-growth theories are based on the economic consideration that in parallel with the development of the modern economies, GDP and consumption expenditure increasingly ignore several elements of subjective welfare and sustainability, while they admit a variety of performances the positive impact of which on welfare is questio

nable. According to the interpretation of Jackson (2009) after an income per capita of USD 15,000 income growth no longer improves the welfare of the individuals and has hardly any effect on life expectancy or infant mortality. The data approximating production and consumption do not include, for instance, the social needs of people, the welfare impact of entertainment and leisure opportunities, the importance of access to information and digital assets, the importance of the health condition and the welfare impact of appreciation and learning.

According to the calculations of Victor and Jackson, with the current population and economic growth dynamics, the carbon intensity of GDP should decline by 7 percent annually, to reach the emission level of the 2000s by

2050. Thus, according to their conclusions, no green growth framework or climate protection policy whatsoever is able to offset climate change while maintaining growth (Jakob and Edenhofer, 2014). Accordingly, an economy should be created in which the biophysical reserves and processes are stable, and the raw material and energy flows remain within the ecological limits (Schneider et al., 2010).

Based on Victor’s (2011) LowGrow model, growth “respects” the global limits of the global environment, i.e. it runs into