The term 'work' has been  used in this model in the sense of economic activity to include not only work done by people but also by machines. The model shows 8 positive feedback loops that reinforce work and the need to work. From the perspective of physics, civilisation can be described as a MECHANISM FOR USING ENERGY AND DOING WORK.  

Work, however, has some unavoidable consequences. The second law of thermodynamics tells us that any ‘work’ requires the use of energy and that DOING WORK entails the generation of WASTE HEAT. The laws of physics also tell us that CO2 emissions from burning fossil fuels will cause global warming. These unintended and unavoidable consequences are highlighted in the model by prominent arrows.

Can the structure of this system be changed to avoid a foreseeable collapse of civilisation?

Modern industrial civilisation has created massive interdependencies which define it and without which it could not function. We all depend on industrial farming to produce the food we eat, we depend on gasoline being available at the gas station,  on the availability of electricity and even on the bread supplied by the local baker. Naturally, we tend to support the institutions that supply the amenities and goods to which we have become accustomed: if we get our food from the local supermarket, it is likely that we would be opposed to it’s closure. This means that the economic system that relies on continuous growth enjoys implicit societal support and that nothing short of environmental disaster or a shortage of essential raw materials will impede it’s growing indefinitely. It is not hard to work out the consequences of this situation!

Wealth can be seen as the factories, infrastructure, goods and services the population of a nation dispose of. According to Tim Garrett,  a scientist who looks at the economy from the perspective of physics, it is existing wealth that generates economic activity and growth. This growth demands the use of energy as no activity can take place without its use. He also points out that the use of this energy unavoidably  leads to concentrations of CO2 in the atmosphere.  All this, Tim Garrett says,  follows from the second law of thermodynamics.  If wealth decreases then so does economic activity and growth. The CLD tries to illustrate how wealth, ironically, now generates the conditions and feedback loops  that  may cause it to decline. The consequences are  inevitably economic  stagnation (or secular recession?). 

You can read about the connection Tim Garrett makes between 'Wealth, Economic Growth, Energy and CO2  Emissions' simply by Googling 'Tim Garrett and Economy'.

Cutbacks can have a counterintuitive effect. The government knows precisely how much it custs in spending. However, it cannot know the extent to which tax revenues shrink in a non-linear complex economic system as the economy contracts. In addition, the treasury has to spend more as automatic stabilizers activate and payments are made to an increasing number of unemployed workers. The effect of this is that initially the deficit shrinks, but later it rises as tax revenues fall short of expectations and more spending takes place. The ironic part is that often the very indicator that promted austerity measurs, the defcit to GDP ratio, becomes worse than it was at the outset. We could observe this in Spain and Portugal where planned deficits have been repeatedly missed, as austerity measures  (fiscal cutbacks) were introduced to deal with the effects of  the 2008 financial crisis.